After being offered a place to live by an elderly Mesa man, 41-year-old Henry Eric Young decided to show his gratitude by allegedly beating the man into critical condition.

Police say they found 81-year-old Gene Fitzsimmons in his car on the 700 block of East First Avenue in Mesa about 7:30 p.m. Tuesday. He was covered in blood and only able to moan in response to officers.

Across the street, they found Young -- who had been living with Fitzsimmons at his home -- coming out of a halfway house. His hands were swollen and there was blood on his clothes. Police also searched Fitzsimmons' East Mesa home, where officers found large amounts of blood throughout the house.

Mesa Police spokesman Detective Steve Berry said it's not yet clear whether Young had previously stayed in the halfway house or was visiting people he knew.

Young's rap sheet already includes convictions out of Hamilton County, Ohio, for arson, sexual battery, gross sexual imposition, reckless driving, and disorderly conduct by fighting or threatening, among others, according to court records.

His convictions in Arizona thus far include DUI, failure to register in Arizona, trespassing, and using fictitious plates, according to the courts.

Fitzsimmons' neighbors said he had taken Young into his home, as they told police he often took in troubled men in an attempt to help them.

Young had been seen driving with Fitzsimmons earlier in the day, and when he was asked why he had beat up a man nearly twice his age, he didn't have an answer for police.

As of about 2 p.m. today, Berry says Fitzsimmons was in critical condition, with two broken ribs, a broken nose, and bleeding from the brain.

Young was booked on one felony count of aggravated assault.