The day before opening statements were set to begin in the trial of the first of seven suspects charged in last year's murder of a Norcross teenager, one of those defendants has taken a plea deal in the case.

Timothy Johnson admitted in Gwinnett Superior Court Tuesday that he was the getaway driver in the home invasion and murder of 15-year-old Nicholas Jackson Jr. The teen and his sister were home alone when five men burst in and shot him through his bedroom door.

Johnson has pleaded guilty to lesser charges in exchange for his testimony against 36-year-old Jason Dozier. 

"As we move sort of up the ladder in culpability, the plea deals are going to become less and less," says District Attorney Danny Porter.

He tells WSB's Sandra Parrish Dozier is being tried separately for technical reasons.  The other five defendants will be tried together before the end of the year.

Porter doesn't believe any of the defendants set out to commit a murder that night.

"The robbery was the plan, Nicholas Jackson got in the way," he says.

Investigators say Jackson's father, Nicholas Jackson Sr., is a known drug dealer and was arrested on federal drug charges after the murder.  They believe the suspects knew the elder Jackson kept large amounts of cash in the home.

The elder Jackson is expected to take the stand today.

Others suspects arrested in the case include 23-year-old Michael Davis of College Park,  32-year-old Anthony Lumpkin of Douglasville, and 46-year-old Eddie Lewis Green, 31-year-old Darrez Chandler, and 20-year-old Reco West all from Atlanta.

Nicholas Jr. was valedictorian of his middle school and a freshman football player at Norcross High School.