Story highlights Paul Kitterman was last seen by his son and friends waiting outside a stadium bathroom

He has been missing since Thursday night

The 53-year-old Broncos fan was attending his first game in person

His friend says he's very loyal to his son, wouldn't just walk away

As Jarod Tonneson went into a bathroom during the Denver Broncos game this past Thursday night, his father, Paul Kitterman, waited outside.

When Tonneson came out of the restroom on the second level of the stadium, his dad wasn't there.

Tonneson went back to their seats in section 230. No sign of him.

He went to check with the friends they had come to the game with and met up with at halftime. There was more room in their section and perhaps Kitterman, who was attending his first game, would be there. No sign of him.

There was no cell phone to call. Kitterman, 53, doesn't particularly care for them.

They went to the spot where they were supposed to meet after the game. No sign of him.

It wasn't like Kitterman to just take off.

"He wouldn't leave Jarod for all the money in the world," Tia Bakke, one of the friends who went to the game, said Monday night. "He had plans the next day. He had things he wanted to do."

Kitterman doesn't have any health problems, Bakke said.

Sonny Jackson, a spokesman for the Denver Police Department, said a witness remembers seeing Kitterman in the stadium during the third quarter.

Jackson said investigators were looking through security video from Sports Authority Field at Mile High.

According to CNN affiliate KUSA , Kitterman also didn't care for credit cards and was carrying about $50 in cash.

"Paul is the best guy you could ask for. They don't make them like Paul anymore," said Bakke, who met Kitterman through her boyfriend, who has known the missing man for a decade.

Kitterman was a passenger for the two-hour drive from Kremmling to Denver, KUSA reported.

The group that operates Sports Authority Field at Mile High, Stadium Management Company, said it is working with the Denver police investigation.