An ex-Marine is trying to escape the worst penalties in the shooting death of SEAL sniper Chris Kyle, subject of the blockbuster Hollywood film “American Sniper,” by pleading insanity — but the prosecution has brought forward an expert witness who contradicted this claim in recent testimony.

The trial of Eddie Ray Routh, charged with killing Kyle and his friend Chad Littlefield, continued on Friday as prosecutors called rebuttal witnesses. The insanity defense is the chief strategy of Routh’s attorneys, who rested their case the day before, according to an Associated Press report.

However, Dr. Randall Price, a forensic psychologist testified Friday that while Routh had a paranoid disorder made worse by consuming alcohol and marijuana — a condition he called “cannabis-induced psychosis” — he nevertheless “did know what he was doing was wrong, and he did it anyway,” Price said according to the report.

The defense had produced their own witnessed, Dr. Mitchell H. Dunn, who testified the day before that Routh had schizophrenia and showed signs of the illness at least two years before the shootings, which happened back in February 2013. Dunn said that Routh had reported seeing acquaintances turn into pig-human hybrids.

However, Price countered that Routh appeared to be “setting the stage” for an insanity defense, claiming that Routh’s idea for pig-human hybrids may have come from a “Seinfeld” episode which involved the character Kramer finding in a hospital what he claims is the elusive “pig-man,” or the TV show “Boss Hog.”

While Price said he couldn’t say for a fact that he had seen that particular episode of Seinfeld, he said he did know that Routh had watched “Boss Hog.”

Another prosecution expert, Dr. Michael Arambula, agreed that the defendant’s actions didn’t meet the definition of insanity under criminal law. Arambula further added that “any time intoxication is present, the game is over,” the report states.

If he were to be convicted, Routh, 27, would face a mandatory life sentence in prison without parole. However, although the death penalty is allowed in the state of Texas, where he is being tried, prosecutors won’t seek it.

If Routh is found not guilty by reason of insanity, the judge can have him committed rather than jailed.

The trial has been complicated by box office hit “American Sniper” directed by Clint Eastwood, where Hollywood star Bradley Cooper portrays the life of Kyle and his actions as a Navy SEAL and the sniper with the most confirmed kills in U.S. military history. The movie is still very much in the national spotlight, as the film has been nominated for several Academy Awards, including Best Picture, which it could win this Sunday night when the Oscar ceremonies take place.