MILWAUKIE, Ore. (KOIN) — Daniel Cristofolo would have turned 40 in April. His family said he’s a homebody, an avid fisherman and did a lot of landscaping around the Woodstock and Eastmoreland area.

But he vanished shortly before Christmas 2015, and though his mother calls his cell phone every day, she believes he’s passed.

Mindy Amundson said her son was last seen December 14 at his house on Southeast 41st Street in Portland. The front door of his house was later found ajar.

The house, his trucks, his boats and his cat — named Chicken — are still waiting for him to come back.

“He would never leave his cat behind,” Amundson told KOIN 6 News. “He loved his cat.”

She said Cristofolo was a sweet son, an independent, adventurous man who would leave on camping and fishing trips for weeks at a time. He had ADHD and suffered from high highs and low lows, she said.

But she also added, “He’s a pit bull when he gets mad. I’m curious to know what went on.”

Daniel Cristfolo in an undated photos posted to the "Help Find Daniel" Facebook page, July 8, 2016

Not long before he was last seen, Cristofolo had some kind of altercation and knocked on a neighbor’s door. He wanted help to hide his truck.

“He had broken his hand, he was bleeding,” the neighbor — who asked not to be identified — told KOIN 6 News. “He said that’s why he couldn’t get the garage door open and he was afraid that they were going to be after him.”

The neighbor said Cristofolo seemed worried about whoever it was he fought.

Help Find Daniel – Facebook page

After he vanished, his family began posting flyers. His red Ford F-150 was found on January 1 when a relative recognized it at Lewis & Clark Park by the Sandy River.

Police found no evidence of foul play, but both his mother and the neighbor think otherwise.

“I thought, ‘Oh my gosh, they got him,'” the neighbor said. “Because, I mean, he beat somebody up so bad he broke his hand.”

Mindy Amundson agrees.

“I think that they did him in and I think he’s passed,” she said. Asked who she thinks it is, she said, “These people, whoever they are.”

The family is offering a $5000 reward for information that solves the case.Anyone with information is asked to call the Portland Police at 503.823.0797. The case number is 15-439070.