The family of a student who had a sexual affair with Burbank Unified middle school teacher Amy Beck has filed a lawsuit against her husband, a Los Angeles police officer, claiming he threatened to kill the teenager with his department-issued gun.

The family claims that when Nathaniel Beck learned his wife was having an affair with the then-14-year-old student at Jordan Middle School, he threatened to kill him, according to the lawsuit filed this week in Los Angeles County Superior Court.

It also alleges that Nathaniel Beck "shirked his mandatory duty" when he failed to report the "sexual molestation," and that the Los Angeles Police Department, which is also named as a defendant in the lawsuit, broke the law by failing to adequately "supervise, train or discipline" him.

Amy Beck, 34, turned herself in to police in March and confessed to having had a sexual relationship with her student. The student, now 16, has not been identified.

The former sixth-grade teacher — herself the mother of three young children — pleaded no contest to two charges of unlawful sex with a minor and is serving a two-year prison sentence. She will also have to register as a sex offender for life.

The liaison took place from March to September 2009, and involved multiple sex acts at Amy Beck's Burbank home and on the Jordan Middle School campus, according to the lawsuit.

It was preceded by more than two years of grooming wherein Amy Beck hired the student to babysit her children, took him to Universal Studios and chose him as her classroom aide, according to the complaint.

She made repeated sexual advances, kissing and fondling the student, and telling him she wanted to "teach him" about sex, the lawsuit alleges.

A lawsuit filed by the family in U.S. District Court for the Central District of California that alleged the school district failed to safeguard the student from an aggressive sexual predator was voluntarily dismissed in December.

"The fundamental reason is, when looking at all the facts, it became clear to us that violations we are alleging are primarily state law violations," said Lon Isaacson, an attorney representing the family.

Nancy Doumanian, attorney for the Joint Powers Authority, Burbank Unified's insurance liability pool, declined to comment on the lawsuit, as did the LAPD.

The new lawsuit again names Burbank Unified and Jordan Middle School Principal Sharon Cuseo.

"We do feel there is a grave lapse in the administrative oversight of the school district that permitted this horrific series of criminal assaults on this child to occur over a long period of time," Isaacson said.