LA CROSSE, Wis. (WKBT) -

A La Crosse County judge set a $500,000 cash bond on Monday for a man accused of killing a Grant County cab driver.

Timmy Johnson Jr., 25, was involved in a crash with a reported stolen vehicle on Highway 35 in Holmen early Friday morning, according to charges.

Johnson faces several charges, including reckless endangerment, fleeing officers and bail jumping.

Authorities said they found 79-year-old Merle Forbes in the trunk of the stolen vehicle driven by Johnson after the crash.

"Early indications from preliminary autopsies show that the injuries from the assault is leaning towards the cause of death," La Crosse County Medical Examiner Tim Candahl said.

"The allegations are that he robbed and stabbed a cab driver in Grant County, and then that individual was then found in the trunk of that vehicle," prosecutor Jessica Skemp said in court Monday afternoon. She said homicide charges against Johnson are being investigated are likely. He has not been formally charged.

Prosecutors said Johnson allegedly killed Forbes because Forbes called police when Johnson allegedly stiffed him for a $90 cab fare from Darlington to Boscobel last August.

Johnson's attorney said his client has a history of mental illness.

"Since Mr. Johnson was booked into the jail on Friday he's been in a cell by himself, a cell in the medical unit, and he's been on the 15 minute watch. He has also told me that crisis intervention has spoken with him," said Tom Laconte, Johnson's public defender.

Johnson was released from the Grant County Jail Thursday morning, the day before Forbes was found dead.

Johnson's defense said he is supposed to be on medication for his mental health issues, but was not given any while in jail for 36 days.

His next court date is scheduled for Thursday afternoon.