LUDINGTON, Mich. -

A man whose wife took the witness stand against him in the killing of a Michigan state trooper has refused to let his own lawyer cross-examine her.

Eric Knysz (NIZE) also apologized Monday to his wife, telling Sarah Knysz he loves her and regrets putting her "through this." The jury was out of the Ludington courtroom when he spoke.

The 20-year-old is on trial on a first-degree murder charge in the killing of 43-year-old Trooper Paul Butterfield II during a traffic stop in September.

In her testimony, Sarah Knysz said Butterfield may have stopped them for a loud muffler. She says her husband had stolen guns with him.

The 21-year-old woman is serving two to five years pleading guilty to being an accessory to the killing.