OLATHE (AP) — Four men charged with killing a suburban Kansas City gun store owner will face additional charges.

The suspects were already charged with first-degree felony murder in the January shooting death of Jon Bieker in Shawnee. He was killed while defending his wife during a robbery at the She’s A Pistol gun store. His wife, Becky Bieker, suffered only minor injuries.

Jon Bieker spent most of his early years living in WaKeeney.

A preliminary hearing scheduled for Monday was postponed until July 27 at the request of defense attorneys.

The Kansas City Star reports the suspects — Londro E. Patterson III, Deanthony A. Wiley, Nicquan K. Midgyett, and Hakeem W. Malik, — are now also charged with attempted aggravated robbery, conspiracy to commit aggravated robbery and aggravated battery.

All four suspects are being held in the Johnson County Jail.