MADISON, Wis. -- A new court document said a Mount Horeb man charged in a deadly hit-and-run confessed to hitting something as he was talking on the phone but didn't want to stop and see what it was.

That's according to a criminal complaint filed Friday against Justen Brock, 30, in the death of Gregory McCullick, 20.

The criminal complaint alleges he was on the cell phone with his ex-girlfriend when he told her he struck something, and despite her pleas did not stop.

Brock was formally charged Friday with hit-and-run resulting in the death of McCullick.

Brock is not charged with drunken driving, but prosecutors said they believe he was.

Last Saturday, authorities said McCullick and Brock were both at a wedding reception at a Verona farm when McCullick left on foot and Brock by car, although a shuttle bus had been provided by the groom's father.

The complaint said Brock drove to his ex-girlfriend's but got upset and sped off. She then called him by cell phone, and told investigators she heard something shocking.

According to the complaint, the defendant said words to the effect of, "Oh my God, something just jumped out at me and I just hit it."

Brock's former girlfriend told him to go back and see what he hit, but Brock said he was not going to do that, the complaint said.

"He then reappeared at (his ex-girlfriend's) home, and informed her that he was too scared to see what he had hit and stated ... he was just going home," said Mike Verveer, assistant district attorney in Dane County.

Deputies later found his car hidden in some trees. It had damage to the front end, authorities said.

Brock's attorney argued for a signature bond, saying Brock should be released so he can keep working to support his 4-year-old son.

He also told the judge that Brock tried to turn himself in, but deputies just arrested him. Detectives disputed that, WISC-TV reported.

Cash bail was set at $15,000.