PUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


UNITED STATES OF AMERICA,               
                 Plaintiff-Appellant,
                 v.                             No. 00-4780
GEORGE W. CEPHAS,
              Defendant-Appellee.
                                        
           Appeal from the United States District Court
         for the Eastern District of Virginia, at Richmond.
            Richard L. Williams, Senior District Judge.
                           (CR-00-240)

                       Argued: April 6, 2001

                      Decided: June 19, 2001

      Before WIDENER and WILKINS, Circuit Judges, and
       Patrick Michael DUFFY, United States District Judge
     for the District of South Carolina, sitting by designation.



Vacated and remanded by published opinion. Judge Widener wrote
the opinion, in which Judge Wilkins and Judge Duffy joined.


                            COUNSEL

ARGUED: Alessandra DeBlasio, Assistant United States Attorney,
Alexandria, Virginia, for Appellant. William Hartman Sooy, Rich-
mond, Virginia, for Appellee. ON BRIEF: Helen F. Fahey, United
States Attorney, Alexandria, Virginia; Michael T. Hosang, Special
Assistant United States Attorney, Richmond, Virginia, for Appellant.
2                       UNITED STATES v. CEPHAS
                               OPINION

WIDENER, Circuit Judge:

  The government appeals from the district court’s order granting
George Cephas’s motion to suppress marijuana, crack cocaine, and
two firearms seized by police officers during a search of Cephas’s
apartment. For the reasons stated below, we reverse.

                                    I.

   On June 14, 2000, Richmond Police Sergeant Scott Shapiro was on
patrol in a marked police car when a concerned citizen (informant)
flagged him down.1 The informant claimed to have just come from an
apartment where a 14 year old girl was smoking marijuana with a
man named Cephas.2 The informant also reported that the apartment
in question was one block away from where Sergeant Shapiro was
then located. Sergeant Shapiro promptly went to investigate at the
address indicated by the informant, 2413 Lamb Avenue,3 which he
found to be a house divided into apartments.

   Sergeant Shapiro knocked on the front door of the house, which
apparently opened to a common area, and his knock was answered by
a woman. In response to Sergeant Shapiro’s inquiry, the woman told
him that a man named Cephas rented the apartment at the top of the
stairs to the right. Sergeant Shapiro then went up the stairs and
knocked on Cephas’s door. The door was opened by a man, whom the
    1
     During his testimony at the suppression hearing, Sergeant Shapiro
stated that he did not know the informant. Shapiro had never seen the
informant before or after June 14, 2000. Further, Shapiro declined to pro-
vide a physical description of the informant, fearing Cephas then would
know who had spoken to the police.
   2
     Shapiro testified at the suppression hearing that the informant told
him the girl "was smoking marijuana with two older gentlemen named
Cephas." The government’s brief and the district court’s findings of fact,
however, both say that the informant told the officer about only one man
named Cephas.
   3
     The district court refers to this location as 2403 Lamb Avenue. We
treat this difference as a typographical error.
                        UNITED STATES v. CEPHAS                         3
district court determined was Cephas. Sergeant Shapiro observed both
that a young girl was sitting in the apartment and that "a strong smell
of marijuana was coming from the apartment."4 When Sergeant Sha-
piro asked if he could come inside to speak with Cephas, Cephas tried
to slam shut the door. Sergeant Shapiro then pushed his way into the
apartment.

   Once inside the apartment, Sergeant Shapiro observed eight or nine
people and what he believed to be a marijuana "roach" in an ashtray.
He then told the people in the apartment to stay in the living room
where they were, and he called for additional officers. Within ten
minutes or so, more officers arrived. The officers then secured the
location by patting down the occupants of the apartment which they
considered conducting a protective sweep of the area in which they
were sitting.

   Sergeant Shapiro also called one Detective O’Connor to have his
help in quickly obtaining a search warrant allowing a search of the
apartment. O’Connor obtained the search warrant at approximately
4:30 p.m. and arrived with it at Cephas’s apartment approximately
one and one-half hours after Sergeant Shapiro first entered it.

   While the officers were waiting for the search warrant, the eight or
nine occupants were allowed to get glasses of water but were not per-
mitted to use the telephone, and they were only permitted to use the
bathroom if they first consented to be searched. Also during this time,
Cephas refused to consent to a search of the apartment and made
repeated complaints about the presence of the officers. Cephas also
stated that as long as he was in his own home with his own family
there was nothing illegal about having a little marijuana.

   Either during the protective sweep or after the search warrant
arrived, officers found in the apartment several "cigar blunts" contain-
  4
   The district court found that as Sergeant Shapiro "approached the resi-
dence, which contained numerous apartments, he smelled marijuana."
The district court also found that when Cephas opened his door, the offi-
cer "still smelled marijuana." We find nothing in the record to support
that Shapiro smelled the marijuana smoke as he "approached the resi-
dence."
4                        UNITED STATES v. CEPHAS
ing marijuana, a plastic bag containing individually wrapped pack-
ages of a substance later determined to be crack cocaine, a .22 caliber
pistol, a 12 gauge shotgun without a serial number, and a police scanner.5
Cephas was subsequently indicted on one count of possession of
cocaine base in violation of 21 U.S.C. § 844, one count of possession
of marijuana in violation of 21 U.S.C. § 844, two counts of possession
of a firearm by a convicted felon in violation of 18 U.S.C.
§ 922(g)(1), and two counts of possession of firearm by a user of con-
trolled substances in violation of 18 U.S.C. § 922(g)(3).

                                     II.

   We review the district court’s findings of historical fact for clear
error. See Ornelas v. United States, 

, 699 (1996). We
review de novo the ultimate questions of reasonable suspicion and
probable cause to make a warrantless search or seizure. See 

, 699.

   The district court held a suppression hearing on September 3, 2000,
and heard testimony from Sergeant Shapiro and from Earl Camp, one
of the police officers who responded to Sergeant Shapiro’s call for
assistance after he entered the apartment. The district court sup-
pressed the evidence seized from Cephas’s apartment because it con-
cluded that the anonymous tip which led Sergeant Shapiro to the
house in which Cephas rented an apartment was constitutionally
insufficient under Florida v. J.L., 

(2000).

    The issue in J.L. was whether an anonymous tip gave officers rea-
    5
    The district court made a finding of fact that, as Cephas asserts, the
marijuana, cocaine and shotgun were found during the protective sweep.
The government argues that these items were found only after the war-
rant arrived. It appears that the only evidence in the record supports the
view that these items were not found until after the warrant arrived, but
we need not decide whether the district court’s finding of fact on this
issue was clearly erroneous because it is not necessary to the question
now before us. Remarkably, the search warrant is not included in the
record on appeal. Upon inquiring, we are also advised that is not a part
of the record retained in the district court, although a copy of the warrant,
less the return is in the joint appendix.
                        UNITED STATES v. CEPHAS                         5
sonable suspicion to stop and frisk an individual reported to be carry-
ing a firearm. The anonymous tip at issue in the case was made by
telephone to the Miami-Dade Police and reported that a young black
male wearing a plaid shirt and standing at a particular bus stop was
carrying a gun. 

. The officers who responded to
the tip saw three young black men, one wearing a plaid shirt, at the
bus stop. 

. Apart from the tip, the officers had
no reason to suspect any of the three were engaging in illegal conduct.

. One of the officers approached J.L., who was
wearing the plaid shirt, had him put his hands on the bus stop, frisked
him, and seized a gun from his pocket. 

. Because
the Court concluded that the anonymous tip at issue, without more,
was insufficient to create the reasonable suspicion that would have
allowed the officers to stop and frisk J.L. as allowed under Terry v.
Ohio, 

(1968), it held the search invalid. 

.

   In this case, apparently, the district court analogized Sergeant Sha-
piro’s appearance at the house in which Cephas had an apartment, or
at Cephas’s apartment, to a Terry stop and frisk.6 The district court
concluded that because the tip about Cephas was given by an anony-
mous individual and at the moment it was given to Shapiro was with-
out sufficient indicia of reliability, the tip did not create a reasonable
suspicion permitting Shapiro to conduct what the district court termed
"an investigatory stop," finding the tip was not "reliable in its asser-
tion of illegality." Therefore, the court ordered not only that the seized
marijuana, crack cocaine, and firearms were inadmissible, but that the
evidence that Sergeant Shapiro smelled marijuana in and around
Cephas’s apartment was also inadmissible.

                                   III.

   At this point, it is of some consequence that we recount the situa-
tion which faced Sergeant Shapiro. He had been told, face to face, by
an informant, that there probably was occurring a serious felony
  6
   As the district court said at the suppression hearing, "It seems to me
that the only issue in this case is why did Sergeant Shapiro appear at
2403 Lamb Avenue in the first instance"? This statement was later
repeated in the same hearing.
6                       UNITED STATES v. CEPHAS
under Virginia law, furnishing illegal drugs to an infant, with a ten-
year prison term minimum penalty. He was given the exact address
of the nearby apartment in which the illegal activity was taking place,
the name of Cephas, and the participation of an infant girl; and the
informant was no longer at hand. Shapiro either had to walk away
from the crime or investigate. He investigated. We are of opinion his
investigation was lawful and not in violation of the Fourth Amend-
ment, as we will set forth below.

                                    A.

   We first decide whether Sergeant Shapiro’s conduct from the time
he received the tip until the point at which Cephas attempted to shut
his apartment door implicated the Fourth Amendment. Here, we dis-
agree with the district court’s application of J.L. to this case. J.L. does
not establish a rule that when officers receive a tip that by itself would
not establish reasonable suspicion to conduct a Terry stop they are
therefore constitutionally barred from conducting any investigation
pursuant to that tip. We read nothing in J.L. that forbade the officers
in that case to appear at the bus stop in an attempt to investigate the
tip.7

   Thus, Sergeant Shapiro’s appearance at the address given to him by
the informant was not forbidden by J.L. Neither was it forbidden by
another rule of law of which we are aware. Cf. United States v.
Christmas, 

, 145 (4th Cir. 2000) (explaining that a "com-
munity might quickly succumb to a sense of helplessness if police
were prevented from responding to the face-to-face pleas of neighbor-
hood residents for assistance").

   Sergeant Shapiro was given a face-to-face tip that a felony, deliv-
ery of drugs to a minor,8 was likely being committed by a man or men
    7
    The officers then would have been free, for example, to attempt to
engage the youths in conversation. See Florida v. Bostick, 

,
434 (1991) (stating that the Fourth Amendment is not implicated "simply
because an officer approaches an individual and asks a few questions,"
so long as the encounter is consensual).
  8
    Va. Code Ann. § 18.2-255 provides, in relevant part, that "it shall be
unlawful for any person who is at least eighteen years of age to know-
                        UNITED STATES v. CEPHAS                           7
named Cephas at a nearby apartment, and the tip was given by some-
one who claimed just to have left that apartment. Even if the tip by
itself would not have been sufficient to establish reasonable suspicion,
we fail to see how the officer properly could have done anything other
than follow up the tip.

   A voluntary response to an officer’s knock at the front door of a
dwelling does not generally implicate the Fourth Amendment, and
thus an officer generally does not need probable cause or reasonable
suspicion to justify knocking on the door and then making verbal
inquiry. As we recently reiterated in a case involving officers who,
having knocked at the defendant’s door in order to, under court order,
return a handgun taken from him at an earlier traffic stop, observed
evidence of criminal wrongdoing through the front window of the
defendant’s house:

     Absent express orders from the person in possession against
     any possible trespass, there is no rule of private or public
     conduct which makes it illegal per se, or a condemned viola-
     tion of the person’s right of privacy, for any one openly and
     peaceably . . . to walk up the steps and knock on the front
     door of any man’s "castle" with the honest intent of asking
     questions of the occupant thereof—whether the questioner
     be a pollster, a salesman, or an officer of the law.

United States v. Taylor, 

, 909 (4th Cir. 1996) (quoting
Davis v. United States, 

, 303 (9th Cir. 1964).

ingly or intentionally . . . distribute . . . marijuana to any person under
eighteen years of age who is at least three years his junior . . . ." Va.
Code Ann. § 18.2-255(A). Virginia fixes the penalty for offenses under
this statute at imprisonment for not less than ten nor more than fifty
years. See Va. Code Ann. § 18.2-255(A). The act of an adult handing a
marijuana cigarette to a juvenile would implicate § 18.2-255 because the
state defines "distribute," as proscribed in § 18.2-255, to mean "to deliver
other than by [lawfully] administering or dispensing a controlled sub-
stance." Va. Code Ann. § 54.1-3401. The tip that men were smoking
marijuana with a juvenile would also have implicated at least two misde-
meanor offenses: possession of marijuana under Va. Code Ann. § 18.2-
250.1, and encouraging an act rendering a child delinquent under Va.
Code Ann. § 18.2-371.
8                       UNITED STATES v. CEPHAS
   In this case, there is no evidence that Cephas’s act of initially open-
ing his door to Sergeant Shapiro was anything but voluntary. The offi-
cer first knocked at the front door of the house in which Cephas
reportedly rented an apartment. A woman answered and said that a
man named Cephas rented an upstairs apartment. When Sergeant Sha-
piro then walked from the front door of the house up the stairs to
Cephas’s apartment door, he apparently did so through an area com-
mon to the several separate apartments in the house, an area where
any pollster or salesman could have presented himself. In any case,
Sergeant Shapiro’s movement from the front door of the house to
Cephas’s apartment door was made with the obvious consent of the
woman who answered his knock at the front door of the house and
who then directed him up the stairs. Sergeant Shapiro testified that he
next knocked on Cephas’s door and the door then opened. Nothing in
the record suggests the officer used his authority to command that the
door be opened. Indeed, the district court found that Cephas was not
aware that it was a police officer who was knocking at his door until
the door was already open.9

   When Cephas opened his apartment door without knowing who
was on the other side, he voluntarily exposed to the public any odors
and such a view as one standing at the door could perceive. None of
Sergeant Shapiro’s conduct up to that point, at which he smelled "a
strong smell of marijuana coming from the apartment" and "saw a
young girl sitting" in the apartment constituted a search within the
meaning of the Fourth Amendment. See 

; see
also Katz v. United States, 

, 351 (1967) ("What a person
knowingly exposes to the public, even in his own home or office, is
not a subject of Fourth Amendment protection"). Thus, it was error
for the district court to suppress evidence that the officer smelled mar-
ijuana in and around Cephas’s apartment.

                                   B.

   Cephas rejected Sergeant Shapiro’s request that he be allowed to
come inside the apartment to talk, and Cephas tried to shut his door
in the face of the officer, something he ordinarily would have had
    9
  The district court found that Cephas "attempted to close the door
when he realized that Sergeant Shapiro was a police officer . . . ."
                       UNITED STATES v. CEPHAS                        9
every right to do. Sergeant Shapiro, on the other hand, then pushed
open the door of the apartment, something he ordinarily would have
had no right to do absent a warrant. The question that we now
address, then, is whether Sergeant Shapiro’s warrantless entry into
Cephas’s apartment was lawful.

   The Fourth Amendment says that the "right of the people to be
secure in their persons, houses, papers, and effects, against unreason-
able searches and seizures, shall not be violated." U.S. Const. amend.
4. Its central requirement is one of reasonableness. See Texas v.
Brown, 460 US. 730, 739 (1983). Warrantless entries into a residence
are presumptively unreasonable. Payton v. New York, 

,
586 (1980). Nevertheless, an exception to the warrant requirement is
made when certain exigent circumstances exist. For example, where
police officers (1) have probable cause to believe that evidence of
illegal activity is present and (2) reasonably believe that evidence may
be destroyed or removed before they could obtain a warrant, exigent
circumstances justify a warrantless entry. See United States v. Turner,

, 528 (4th Cir. 1981).

   Sergeant Shapiro smelled "a strong smell of marijuana coming
from the apartment." Therefore, when Cephas began to close the
apartment door, this odor alone would almost certainly have given
Sergeant Shapiro probable cause to believe that contraband—
marijuana—was present in the apartment. See United States v. Gris-
sett, 

(4th Cir. 1991) (instructing that the odor of mari-
juana coming from a motel room provided exigent circumstances to
justify a warrantless entry).

   The tip given to Sergeant Shapiro provided additional evidence to
support probable cause. Unlike the anonymous telephone tip in J.L.,
the tip in this case was made face-to-face by an individual who
flagged down the officer and claimed just to have left Cephas’s apart-
ment, which was only a block away from where the officer received
the tip. See United States v. Christmas, 

, 144 (reasoning
that face-to-face encounter with informant who provided tip when
close in time and distance from the alleged illegal activity bolstered
credibility of the informant). But the tip alone would not have given
Sergeant Shapiro probable cause to believe that contraband was pres-
ent in the apartment. Unlike J.L., however, the officer here confirmed
10                      UNITED STATES v. CEPHAS
(1) that a man named Cephas indeed had an apartment at the address
reported by the informant; (2) that a young girl indeed was inside the
apartment; and (3) that marijuana, an illegal drug, indeed, was being
smoked in the apartment. See 

(requiring that tip
not only reliably identify the person the tipster seeks to accuse, but
that the tip "be reliable in its assertion of illegality"). Here, the offi-
cer’s corroboration of the tip’s particulars confirms that Sergeant Sha-
piro had probable cause when Cephas attempted to shut his door.

   Having concluded that officer Shapiro had probable cause to
believe contraband was inside the apartment, and that a felony might
well be taking place, we next address the question of whether his
decision to make a warrantless entry into the apartment—rather than
to wait and obtain a search warrant—was justified by exigent circum-
stances. Our inquiry here is guided by United States v. Taylor, 

(4th Cir. 1981), which sets out several factors for analyzing
the question of exigent circumstances, including:

     the degree of urgency involved and the amount of time nec-
     essary to obtain a warrant; (2) the officer’s reasonable belief
     that the contraband is about to be removed or destroyed; (3)
     the possibility of danger to police guarding the site; (4)
     information indicating the possessors of the contraband are
     aware that the police are on their trail; (5) the ready destruc-
     tibility of the contraband.

United States v. 

. The government argues that
Cephas was aware that a police officer was on his doorstep, that mari-
juana is readily destructible, and that Sergeant Shapiro reasonably
believed that the marijuana would have been destroyed had he waited
for a warrant. These reasons alone would have justified his warrant-
less entry. That Sergeant Shapiro also reasonably believed a man or
some men were inside the apartment plying a 14 year old girl with
marijuana only added to the degree of urgency involved in this case.
Therefore, we conclude that after receiving the tip and then smelling
the marijuana coming from the apartment where he saw the young
girl, exigent circumstances justified Sergeant Shapiro’s warrantless
entry. Because exigent circumstances justified Sergeant Shapiro’s
warrantless entry, it was error for the district court to suppress the
marijuana, cocaine, and firearms seized in Cephas’s apartment.
                      UNITED STATES v. CEPHAS                    11
   Accordingly, the order of the district court appealed from is
vacated, and the case is remanded for further proceedings not incon-
sistent with this opinion.

             VACATED AND REMANDED WITH INSTRUCTIONS