DES MOINES, Iowa — The murder trial against Preston Walls is set to begin its third week Monday morning.

Walls is accused of shooting and killing Gionni Dameron, 18, and Rashad Carr, 16 at Starts Right Here, an education non-profit designed to help at-risk youth, on January 23. The founder of Starts Right Here, Will Keeps, was also injured in the shooting.

Walls is charged with two counts of first-degree murder, one count of attempted murder, one count of willful injury, and one count of criminal gang participation.

Last Friday, the prosecution focused on the gun used in the shooting. A detective analyzed the gun that was used by Walls in the shooting. He showed that the gun had an automatic switch attached.

A medical examiner also testified last week saying that Carr had been shot nine times and Dameron had been shot 13 times.

The prosecution is nearing the end of its witness list and the defense only has one name on its list, Preston Walls.

Another teen charged in the shooting, Bravon Tukes, is being tried separately. Investigators say Tukes drove Walls to and from the shooting. Tukes’ trial is scheduled for October. He faces the same charges as Walls.