OMAHA, Neb. — A judge overseeing a trial that got underway Friday must decide if the Nebraska prison system should have to release to the public disturbing pictures drawn by a serial killer who was later executed.

Mark Pettit, a former investigative reporter who wrote a true-crime book about convicted child killer John Joubert, is suing to force the Nebraska Department of Correctional Services to release two drawings in which Joubert purportedly depicted his fantasies to kill again.

Prison system officials have refused to release the drawings, citing confidentiality laws.

Joubert was executed in 1996 for the fatal stabbings of two Bellevue-area boys, ages 12 and 13, that happened weeks apart in 1983. Following his conviction in Nebraska, a jury in Maine found him guilty of murder in the 1982 killing of 11-year-old Richard Stetson in Portland.

Pettit contends that the public has a compelling interest and a right to see the drawings. He says Joubert told him during a series of prison interviews that he continued to have fantasies about killing children even after being sentenced, Pettit said. He said Joubert expressed the fantasies in two graphic drawings that were confiscated by prison authorities.

In February 1988, Joubert wrote to prison officials authorizing them to release the drawings to Pettit for analysis by a mental health professional. Citing pending appeals to his convictions, prison officials refused to do so.

Last year, ahead of the 30th anniversary of the killings, prison officials again turned down Pettit’s request to make the drawings public, leading Pettit to sue.

In court documents, state prison officials argue that Pettit has no legal claim and has presented no just cause for accessing the drawings. Officials also argue that Pettit has shown “no authorization that would require what he asserts to be personal property of Joubert to be turned over to him.”