A self-described hit man who once told police "I kill people for money" pleaded guilty Monday to eight murders, including the contract killing of a Detroit police officer's wife.

Vincent Smothers pleaded guilty to eight counts of second-degree murder and a gun charge in exchange for a minimum sentence of 52 years in prison. With credit for time served since his arrest, he could be freed when he's about 80 years old.

Smothers, 29, shocked police two years ago when he confessed to the eight Detroit slayings during around-the-clock interrogations. He told investigators his hits were all related to the drug trade except for the final one, the killing of Rose Cobb on the day after Christmas in 2007.

"He's just glad there's closure for everybody," defense attorney Gabi Silver told The Associated Press after the hearing in Wayne County Circuit Court, where jury selection was scheduled to begin Monday for the Cobb slaying.