Police arrested an Oregon State University student over the weekend after a transient was shot in an alley behind the Alpha Gamma Rho fraternity house.

Police said a search of the house found more than two dozen weapons including a .22-caliber rifle that tests determined was used in the shooting.

Dennis Sanderson of Corvallis was shot in the thigh Oct. 14 as he emerged from a trash bin behind the house, where he was looking for returnable cans and bottles.

Police said interviews with fraternity members revealed deep resentment about transients in the alley and a willingness of some members to take shots at them.

Police arrested Joshua Grimes, 19, of the rural Oregon town of Glide, on Saturday and charged him with assault and unlawful use of a firearm.

Investigators said he wasn't the only one present and not the only one to have shot at transients over the past year.

"Alpha Gamma Rho doesn't stand for that sort of behavior," said Josh Wackler, director of chapter development for the national fraternity. "Nor tolerate that sort of behavior."

Sanderson said he had just climbed out of a trash bin when he felt something hit his left thigh.

""It was a unprovoked attack," Sanderson said. "Didn't say anything to anyone."

He went to another fraternity house for help, where a member called 911.

Police searching the alley found a shell casing and an unfired round that matched the caliber and type of bullet in Sanderson's leg.

They said at least two members admitted to having shot at transients with BB guns in the past.

According to the police report, Grimes had told a friend at the fraternity that he had shot Sanderson. The friend had Grimes' rifle in his car when police found it.

Grimes was despondent, according to the report. He had already had a traumatic experience. On Oct. 25, Grimes found the body of a good friend at a neighboring fraternity, an apparent suicide.

Concerned for Grimes' state of mind and welfare, police got a fraternity friend to set up a meeting with Grimes at a McDonald's.

They said Grimes told them, "I didn't mean to hit him."

Another fraternity member told police that he was present during the shooting an that both were "freaked out" that Grimes had hit Sanderson.

"This is something of legitimate concern," said Robert Kerr, coordinator of Greek life at Oregon State University.

Kerr said the issues are understanding homelessness and hunger and finding appropriate ways to interact with transients who live with those problems.

Roundtables involving members of six fraternities will begin next year.

Ryan McKee, a member of a neighboring fraternity, said people go through the trash bins in the alley often but don't leave a mess and generally are friendly.

Grimes is no longer listed on the chapter's Web site as a member.