MADISON, Wis. -

Madison police said they arrested a man who urinated on a tree at an east side park and threatened a man who witnessed the incident while he was walking his dogs.

Police said Thomas J. Olson, 47, was urinating on a tree at O.B. Sherry Park, 22 Leon St., about 9:45 a.m. Wednesday when a 43-year-old Madison man walking his dogs witnessed the act and yelled out, "This isn't a bathroom."

Olson responded with a profane tirade, ending his rant by saying, "Does it look like I have anything to lose?" according to a Madison Police Department incident report.

The dog walker was taken aback as the man zipped up and became more irate, shouting "all types of curse words" as he ordered the concerned citizen to mind his own business, according to the report.

The pet owner threatened to call police as Olson picked up a bike lock and chain and began whirling them about "as if he was swinging nunchakus in a karate movie," according to the report.

The victim said the suspect would walk in his direction, turn back around and return to the picnic table where he had placed his bike, backpack and sleeping bag.

Police said the dog walker was concerned about the suspect's stability and called 911.

The suspect told the dog walker to go ahead and call authorities, repeating, "I've got nothing to lose. I'm out here sleeping in the cold," according to the report.

Olson then grabbed a knife and jammed it into the table top with such force that he needed both hands to extricate it from the wood, police said.

Police said that when an officer arrived, Olson said it was the pet owner who was harassing him. Olson said he had emptied a water bottle on the tree and denied sticking his knife into the table, police said.

The officer saw that there was a noticeable indentation mark on the table and that the wet mark on the trunk was at waist-level, according to the report.

The victim told the officer that there have been problems with homeless people sleeping in the park and he just wanted the man to know that what he was doing, near the tree, wasn't right.

The officer arrested Olson on a disorderly conduct charge, according to the report.