A Prince George’s County man pleaded guilty in federal court to charges in connection with a 2008 home invasion that left three people dead in Springfield, the U.S. Attorney’s Office in Virginia announced Tuesday.

Delonte T. Cook, 35, and co-conspirators masqueraded as police officers during the robbery, according to court documents. The robbers targeted the home because they thought the residents were drug dealers who had a large amount of cash and marijuana on hand.

Two brothers Ryan C. Strope, 26, and Terence J. Strope, 38, were fatally stabbed. An acquaintance, Andres A. Yelicie, 26, was also killed. The home is on Moultrie Road in the Ravensworth Farm neighborhood.

Cook pleaded guilty to conspiracy to commit murder, attempted robbery and using a firearm during a home invasion robbery, according to the U.S. Attorney’s Office.

In the plea agreement, prosecutors and the defense jointly recommended a prison sentence of life in prison plus 20 years for Cook. Sentencing is scheduled for Dec. 16, 2011.

The Stropes were the sons of a retired Arlington County police officer, Christopher Strope.

Another suspect in the case, Jelani Slay, was shot and killed by an off-duty police officer, who Slay attempted to rob at gunpoint in 2009, police said.