Richards v. Wisconsin, 520 U.S. 385, 387, 117 S.Ct. 1416, 137 L.Ed.2d 615 (1997); see also 18 U.S.C. § 3109 (codifying knock and announce re quirement with respect to federal officers). As Judge Widener has recently recognized, the knock and announce requirement serves three purposes: “(1) protecting the safety of occupants of a dwelling and the police by reducing violence; (2) preventing the destruction of property; and (3) protecting the privacy of occupants.” United States v. Dunnock, 295 F.3d 431, 434 (4th Cir.2002) (quoting Bonner v. Anderson, 81 F.3d 472, 475 (4th Cir.1996)). We have recognized that, under appropriate exigent circumstances, strict compliance with the knock and announce requirement may be excused. United States v. Grogins, 163 F.3d 795, 797 (4th Cir.1998) (<HOLDING>). When the authorities “have a reasonable
holding noknock entry justified where officers had reasonable suspicion that entering drug stash house would be dangerous and drug dealer frequenting house could not be found elsewhere holding that when noknock entry is challenged police must prove they had a reasonable suspicion that knocking and announcing presence would be dangerous or futile or inhibit effective investigation of crime holding that officers observation of a known drug dealer approaching the defendants car gave rise to reasonable suspicion holding police may not seize a person who visits a suspected drug house late at night and who stays for only two minutes based only on neighbors complaints of shortstay traffic and where there is no actual evidence of drugs controlled buys reports of known drug users or dealers frequenting the house and so forth holding that defendant staying in abandoned house had no legitimate expectation of privacy in the house despite having a key to the house and the ability to let people in and out of it