A teenager's conviction in the shooting deaths of four people should be thrown out because another man has confessed to the murders, the teen's lawyer said Wednesday.

Kim McGinnis said she was "absolutely confident" that her 16-year-old client, Davontae Sanford, was innocent and that she would ask a judge to throw out his conviction.

Sanford was 14 when four people were shot in a Detroit drug house in 2007. He pleaded guilty to second-degree murder in 2008 and won't get a chance at freedom until he's 53 years old.

Wayne County prosecutors last week turned over a written confession given to police by Vincent Smothers, who is accused in the killings of eight people in six other cases, Smothers' attorney said.

Smothers wrote that he "shot three guys and a female" at the house, and that he and an accomplice took a half-pound of marijuana, $2,000 and a gun that was used in a subsequent killing.

Smothers' lawyer, Gabi Silver, does not dispute that the statements were made.

"But there hasn't been a determination yet if my client's statements were voluntary," Silver said.

McGinnis said the teen was a suspect in the quadruple murder because he lived in the neighborhood and a detective "sensed that Davontae knew more about the case than he was letting on."

She acknowledged that Sanford confessed to the four killings, but added, "Juveniles have a high rate of false confessions."

"He has one eye. At the time, he was reading at a third-grade level," McGinnis said. "He's an extremely agreeable kid. He wants to accommodate adults in his life."

Prosecutors declined to comment until a court hearing March 18.

A hearing Wednesday to determine whether Smothers should go to trial in two other slayings was postponed until April 22. He told police that he shot two elderly men in Detroit in exchange for $15,000 in May 2007, according to court documents.