MADISON, Wisconsin (AP) -- Bloggers and free speech advocates are calling on prosecutors not to file charges against a teacher arrested for allegedly posting an anonymous comment online praising the Columbine shooters.

In 1999, two Columbine High School students killed 12 fellow students, a teacher, and themselves.

Some were disturbed by the post that police say James Buss left on a conservative blog, but other observers said it was a sarcastic attempt to discredit critics of education spending.

The suburban Milwaukee high school chemistry teacher was arrested last week for the November 16 comment left on www.bootsandsabers.com, a blog on Wisconsin politics. The comment, left under the name "Observer," came during a discussion over teacher salaries, after some writers complained teachers were underworked and overpaid.

Buss, a former president of the teacher's union, allegedly wrote that teacher salaries made him sick because they are lazy and work only five hours a day. He praised the teen gunmen who killed 12 students and a teacher before committing suicide in the April 1999 attack at Columbine High School.

"They knew how to deal with the overpaid teacher union thugs. One shot at a time!" he wrote, adding they should be remembered as heroes.

The comment disturbed at least one teacher, who called police in West Bend, 40 miles north of Milwaukee and home of the blog's administrator. Police traveled to arrest Buss at his home in Cudahy, south of Milwaukee, last week after the blogger gave them the anonymous poster's IP address.

After his arrest, Buss spent an hour in the Washington County jail before he was released on $350 bail. He did not return phone messages and e-mails seeking comment, and it was unclear whether he had a lawyer.

Washington County District Attorney Todd Martens is considering whether to charge Buss with disorderly conduct and unlawful use of computerized communication systems.

"If you look at all the factors in this case, it's pretty clear it would be a mistake to charge," said Larry Dupuis, legal director of The American Civil Liberties Union of Wisconsin. "At worst, it was somebody expressing admiration for somebody who did something reprehensible. But the more reasonable explanation is this is somebody who is trying to mock the conservative view of teacher salaries."

Police Capt. Toby Netko defended the arrest. He said the teacher who complained was disturbed by the reference to "one shot at a time" and other educators agreed it was a threat.

"What happens when you say 'bomb' in an airport? That's free speech, isn't it?" he said. "And people are taken into custody for that all the time."

Donald Downs, a University of Wisconsin-Madison professor and expert in free speech, said that "all sorts of unsavory, controversial speech" are protected by the First Amendment.

"It has to be intended to incite violence" to be illegal, Downs said. "If it's tongue-in-cheek, there's virtually no way they can claim that."

Downs added, however, that the school district might have legal grounds to discipline Buss. The teacher has been placed on paid administrative leave while his school district considers what action to take.

Sara Larsen, superintendent of the Oak Creek school district where Buss has worked since 1994, said she was "dismayed, disappointed and discouraged" by the posting. She had worked closely with Buss when he was president of the teacher's union for three years ending in 2006.

"It's not something that I would have expected any teacher to do. As much as teachers understand the whole situation in Columbine, to reference that is certainly inappropriate," she said.