WICHITA, Kan. (AP) — One of four people charged with killing a Kansas couple has pleaded not guilty and will testify against the other three defendants in exchange for his capital murder charge to be reduced.

The Wichita Eagle reports 19-year-old Brandon Smith appeared in Sedgwick County District Court on Monday in shackles and waived his right to a speedy trial.

The other defendants are Anthony Bluml, Andrew Ellington and Kisha Schaberg, Anthony Bluml’s biological mother. All three are to be arraigned on capital murder charges and could face the death penalty.

The four are accused of killing Roger and Melissa Bluml, who were fatally shot as they sat outside their rural Valley Center home on Nov. 15. Melissa Bluml died the next day, while her husband died about five weeks later.