Former Marine Eddie Ray Routh enters the court after a break during his capital murder trial in Stephenville, Texas in this February 19, 2015 file photo. A jury found Roth guilty February 24, 2015 of murdering Chris Kyle, the former US Navy SEAL whose autobiography was turned into the hit movie "American Sniper". [Photo/Agencies]

STEPHENVILLE, Texas - Eddie Ray Routh was jailed for life without the possibility of parole on Tuesday after a Texas jury found him guilty of murdering Chris Kyle, the former US Navy SEAL whose autobiography was turned into the hit movie "American Sniper."

Routh, 27, was found guilty of fatally shooting Kyle and Kyle's friend, Chad Littlefield, multiple times at a gun range about 70 miles (110 km) southwest of Fort Worth in February 2013.

The jury deliberated for a little more than two hours before reaching a verdict at a court in the rural Texas city of Stephenville.

In closing arguments before the case went to the jury, prosecutor Jane Starnes said Routh acted coldly and deliberately when he waited for Kyle to empty his gun at the range and then ambushed the two from behind before fleeing the scene Kyle's pickup truck.

Defense lawyers argued that Routh, a former US Marine, was a paranoid schizophrenic and should be declared innocent by reason of insanity.

"That is not insanity. That is just cold, calculated capital murder," Starnes said.