Jury selection has begun in Texas in the trial of the man charged with murdering Chris Kyle, the former US Navy SEAL whose best-selling autobiography was adapted into the hit movie American Sniper.

About 800 residents of rural Erath County have been called as potential jurors for the trial of 27-year-old Eddie Ray Routh, who is charged with murdering Kyle and his friend Chad Littlefield at a shooting range about 70 miles south west of Fort Worth on 2 February 2013.

Potential jurors will fill out questionnaires this week, while opening arguments are planned for 11 February.

Judge Jason Cashon told jurors they could serve, even if they saw the movie or read Kyle's book.

Kyle and Littlefield took Routh, a troubled Iraq War veteran, to the shooting range to help him with psychological problems, which Routh's family said were brought on by post-traumatic stress disorder.

Routh's relatives said he was sent to a mental institution shortly before the shootings.

Routh is accused of stealing Kyle's truck after the killings and driving it to the home of Routh's sister, who said he confessed to the crimes. Routh was arrested that day and has been jailed in Erath County on $3m (£2m) bond.

His attorney, Warren St John, said he will try to show Routh was insane at the time of the incident and therefore not guilty of murder.

American Sniper, directed by Clint Eastwood and starring Bradley Cooper, has grossed more than $250m since opening in mid-January and has been nominated for six Academy Awards, including best picture.

Kyle's 160 kills in Iraq are considered the highest count in US military history.

Some critics claim the film glorifies war and sanitises Kyle, who called Muslims "savages" in his memoir. Some have also taken issue with Eastwood's interpretation of the history leading up to the 2003 invasion of Iraq.