STEPHENVILLE, Texas >>  Prosecution rebuttal witnesses are set to take the stand as the trial in Texas of an ex-Marine charged with killing “American Sniper” author Chris Kyle and another man moves closer to jury deliberations.

After the testimony that’s to begin Friday, jurors will hear closing arguments before they start deciding Eddie Ray Routh’s fate. Routh’s attorneys, who are pursuing an insanity defense, rested their case Thursday.

Prosecutors have argued that any history of mental illnesses should not absolve Routh of being accountable for the slayings at a shooting range. They are not seeking the death penalty, so a conviction in the 2013 killings would bring an automatic sentence of life in prison without parole.

If Routh, 27, were found not guilty by reason of insanity, the court could initiate civil proceedings to have him committed.

Routh did not testify at the trial. But jurors heard from a forensic psychiatrist who said Routh has schizophrenia and showed signs of psychosis in the weeks leading up to the killings of former Navy SEAL Kyle and Kyle’s friend, Chad Littlefield.

Routh’s friends and family have testified that his behavior in the weeks before the shootings was increasingly erratic. They said he acted as if he believed that someone was going to hurt him and that the government was listening to him.

The trial has drawn intense interest, partly because of an Oscar-nominated film based on Kyle’s memoir. Kyle made more than 300 kills as a sniper for SEAL Team 3, according to his own count.

After leaving the military, he volunteered with veterans facing mental health problems, often taking them shooting. Kyle had taken Routh to the shooting range after Routh’s mother asked him to help her son.