A man who posted false information on an online encyclopedia linking a prominent journalist to the Kennedy assassinations says he was playing a trick on a co-worker.

Brian Chase, 38, ended up resigning from his job and apologizing to John Seigenthaler Sr., the former publisher of the Tennessean newspaper and founding editorial director of USA Today.

"I knew from the news that Mr. Seigenthaler was looking for who did it, and I did it, so I needed to let him know in particular that it wasn't anyone out to get him, that it was done as a joke that went horribly, horribly wrong," Chase was quoted as saying in Sunday editions of The Tennessean.

Chase said he didn't know the free Internet encyclopedia called Wikipedia was used as a serious reference tool.

The biography he posted, which has since been replaced, falsely stated that Seigenthaler was linked to the Kennedy assassinations and had lived in the Soviet Union from 1971 to 1984.

The entry motivated Seigenthaler to write an op-ed piece for USA Today blasting Wikipedia's credibility. He described himself as a close friend of Robert Kennedy and said he had worked with President Kennedy. He said "the most painful thing was to have them suggest that I was suspected of their assassination."

Seigenthaler said he doesn't plan to pursue legal action against Chase.

He also said he doesn't support more regulations of the Internet, but he said that he fears "Wikipedia is inviting it by its allowing irresponsible vandals to write anything they want about anybody."

Chase said he created the fake online biography in May as a gag to shock a co-worker who was familiar with the Seigenthaler family. He resigned as an operations manager at a Nashville delivery company as a result of the debacle.