Plattsmouth, Neb. ? A man accused of killing his 4-year-old son is now accused of assaulting an officer at the Cass County Jail.

Ivan Henk has been placed in isolation, officials said

Henk is awaiting trial on a first-degree murder charge, accused of killing 4-year-old Brendan Gonzalez. The boy disappeared from his mother’s Plattsmouth home on Jan. 6, 2003, and is presumed dead.

Brendan’s body was never found, even after hundreds of volunteers searched the Sarpy County Landfill for his remains for seven weeks last summer. Authorities believe Henk placed the boy’s body in a trash bin that had its contents emptied into the landfill.

Last week Henk pushed and grabbed a member of the jail staff, Sheriff’s Capt. David Lamprecht said.

Lamprecht said the jail worker suffered bruising to her arms and neck and was taken to a hospital, where she was treated and released.

The jail’s policy will be reviewed to keep similar incidents from occurring, he said.

The Cass County attorney’s office will review reports on the attack and decide what, if any, charges will be brought against Henk.

Henk has had a history of disruptive behavior since his arrest. The first was his outburst in an April 2003 court hearing on unrelated charges that he had killed his son. Henk shouted to the boy’s mother that he killed Brendan “because he was the Antichrist. He had 666 on his forehead.”

Henk also has made other comments to the boy’s mother in court and cut one of his wrists late last August while in jail.