Defendant-appellant Michael Moland appeals the district court's denial of his motion to suppress evidence. Defendant pled guilty to possession and distribution of crack cocaine, subject to this appeal. See 18 U.S.C. § 2; 21 U.S.C. §§ 841(a)(1) & (b)(1)(C). Our jurisdiction arises under 28 U.S.C. § 1291 and we affirm.

On June 5, 1991, a Colorado state judge issued a "no knock" search warrant for Defendant's premises, which resulted in the seizure of crack cocaine. The warrant specifically allowed "forced entry without prior announcement." The state police detectives requested a no knock warrant in order to preserve evidence and to ensure the safety of the officers. In the affidavit supporting the warrant, the officers stated that since 1987 the Aurora/Denver Crack Task Force had executed over 800 warrants resulting in the seizure of over 500 guns. At the suppression hearing, one of the detectives testified that he had previously applied for and received approximately thirty no-knock warrants in other crack cocaine cases.

The district court denied the suppression motion, finding that, although there were no exigent circumstances which would justify a no knock warrant under federal law, the good faith exception applied. See United States v. Leon, 468 U.S. 897, 104 S. Ct. 3405, 82 L. Ed. 2d 677 (1984). On appeal, Defendant contends that the officers lacked exigent circumstances and that Leon should not apply to state officers executing a warrant in violation of federal standards.

In reviewing a motion to suppress, we accept the trial court's findings of fact unless clearly erroneous, but review de novo the reasonableness of the search under the Fourth Amendment. United States v. Allen, 986 F.2d 1354, 1356 (10th Cir.1993).

Federal officials serving a warrant must knock and announce their presence and intent before searching a dwelling, unless notice is likely to result in the destruction of evidence or harm to the officers. 18 U.S.C. § 3109; Ker v. California, 374 U.S. 23, 39-40, 83 S. Ct. 1623, 1633-34, 10 L. Ed. 2d 726 (1962); United States v. Mitchell, 783 F.2d 971, 974 (10th Cir.) cert. denied, 479 U.S. 860, 107 S. Ct. 208, 93 L. Ed. 2d 138 (1986). We have previously held that "specific facts regarding the premises to be searched" are required to show exigent circumstances justifying a no knock warrant under § 3109. United States v. Stewart, 867 F.2d 581, 585 (10th Cir.1989). Although federal charges were ultimately filed, this was a state investigation and under Colorado law no knock warrants may be served if expressly provided for by the issuing magistrate. People v. Lujan, 174 Colo. 554, 484 P.2d 1238 (1971) (en banc) (following Ker v. California, 374 U.S. 23, 83 S. Ct. 1623); see also United States v. Moore, 956 F.2d 843, 849 (8th Cir.1992) (discussing conflict in decisions interpreting Ker ); Wayne R. LaFave & Jerold H. Israel, Criminal Procedure § 3.4(h) (1984). The Colorado Supreme Court later clarified Lujan as holding "that exigent circumstances are always present in searches for narcotics." People v. Arnold, 186 Colo. 372, 527 P.2d 806, 810 (1974) (en banc). Here, the detectives presented the magistrate with statistical evidence on the high probability that crack dealers in the area are armed, but no specific evidence that the Defendant would be armed or that the drugs would be destroyed.

Evidence seized by state officers will be suppressed in a federal prosecution if the search violated the Fourth Amendment. Mitchell, 783 F.2d at 973-74; United States v. Walker, 960 F.2d 409, 415 (5th Cir.1992). The government conceded at the suppression hearing that no exigent circumstances existed to justify a no knock warrant under 18 U.S.C. § 3109. See Stewart, 867 F.2d 581. However, § 3109 does not apply to state investigations by state officers, and the government failed to argue that the search was reasonable under the Fourth Amendment notwithstanding the lack of compliance with § 3109. "We will not consider issues which are raised for the first time on appeal unless a party demonstrates an impediment which prevented raising the argument below." United States v. Dewitt, 946 F.2d 1497, 1499 (10th Cir.1991), cert. denied sub nom. --- U.S. ----, 112 S. Ct. 1233, 117 L. Ed. 2d 467 (1992). The government does not assert any impediment to raising the argument below. As such, we do not address whether the circumstances here violated the Fourth Amendment.

We agree with the district court that even if the warrant was constitutionally unreasonable, which we need not decide, the good faith exception to the exclusionary rule applies. The district court, relying on § 3109 and Stewart, found that the officers lacked particular exigent circumstances. The court denied suppression, though, finding that the officer's testimony was credible, that the state judges were not "rubber stamping" warrant requests and that the officer had previously been granted no knock warrants under similar circumstances.

The Defendant correctly points out that the good faith exception does not apply to the improper execution of a warrant. See United States v. Medlin, 798 F.2d 407, 410 (10th Cir.1986). Leon does apply, however, where the execution was in accordance with the terms of the warrant. Id.; Moore, 956 F.2d at 851. Such was the case here. The exclusionary rule is aimed at deterring police misconduct. Excluding evidence seized by police in good faith reliance on a facially valid warrant would not deter misconduct. Medlin, 798 F.2d at 409 (citing Leon, 468 U.S. at 916-22, 104 S.Ct. at 3417-20). Here, the officer and the state court judge acted with "objectively reasonable reliance" on the Lujan decision in concluding that the no knock warrant would not violate Colorado law or the Fourth Amendment. See Moore, 956 F.2d at 849.

AFFIRMED.

FNThe Honorable Paul H. Roney, Senior United States Circuit Judge, United States Court of Appeals for the Eleventh Circuit, sitting by designation.