A Michigan college student was arraigned Thursday on charges he murdered his father, who remains missing after he disappeared late last month.

Patrick Mikes Jr., 21, of Troy, Mich., pleaded not guilty to murder through his attorney, Christopher Andreoff, the Detroit Free Press reported. The college student is being held in the Oakland County Jail after being arrested Wednesday.

Patrick Mikes Sr., 55, went missing July 27. Authorities are still searching for his body.

The investigation into the father's disappearance led police to arrest the 21-year-old, who attends the University of Notre Dame, according to the Oakland Press.

The younger Mikes told investigators his father went for a bike ride July 27 and never came back, according to the Free Press. The bike hasn't been recovered.

Evidence found at the Mikes' home, including blood with mixed DNA of Mikes Sr. and Mikes Jr., led police to believe that the father was murdered and accuse the son of the crime.

The investigation also led police to believe that the father was assaulted.

They came to that conclusion based on evidence at the scene and a forensic analysis of trace evidence by the Michigan State Police's Forensic Science Division, according to the Oakland Press.

"We had numerous hurdles to overcome for the Oakland County Prosecutor's Office," Capt. Bob Redmond told the paper. "We painstakingly worked through all those items. By getting the warrant we have met the extremely high burden set for us (by the prosecutor). We are confident that Mr. Mikes Sr. was killed by his son."

The son had "some injuries" when police interviewed him Sunday, the paper said.

Mikes Jr. had initially been charged with using his father's credit card after Mikes Sr.'s disappearance, according to the Free Press.

The search for the body is centered on Montrose, Mich., about an hour's drive from Troy, after witness reported seeing the son in the area.

"On Saturday morning, Patrick Mikes Jr. told [his brother] Andrew he was going to look for his father around 9 o'clock in the morning," Redmond told the Free Press. "When he reappeared here in Montrose is when two farmers indicated they saw that vehicle driving slowly up and down their road in their farm country area. That is one of the things that leads us to believe that this is definitely a good area to look."

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