Pima County detectives are investigating if some death threats received by fax this spring by a California state senator might be connected to the Tucson shooting spree that left six dead and Rep. Gabrielle Giffords critically wounded.

A Pima County detective called Sen. Leland Yee's chief of staff on Monday to inquire about some racist faxes Yee received in March or April after he checked into payments made by a California state university to Sarah Palin for a speaking engagement.

"I'm not certain if there is a definite connection" between the threats received by Yee and the Giffords case, Keigwin said. "He referenced that they are seeing similar faxes in their investigation. I think it has similar terminology. I don't know for sure, but he said they are getting very similar faxes."

Deputy Jason Ogan, a Pima County Sheriff's Department spokesman, could not be reached for comment.

Keigwin said Yee received several anonymous threatening telephone messages at his offices and that he dismissed those as angry outbursts by "Sarah Palin fans."

But he said the faxes were far more ominous. One featured a depiction of a noose and said "kill all the Marxists." Others contained the "n" word and a communist symbol, attempting to draw a connection between Yee and the communist government of China.

Keigwin said he described the faxes to the Pima County detective and told him to call Tony Beard, the California State Senate's Sergeant-at-Arms, to learn more about the investigation.

The San Mateo County Times reported that the California Highway Patrol eventually investigated the death threats received by Yee.

Keigwin said he does not believe Giffords and Yee have ever met and knows of no other connection between them. Yee and Giffords are Democrats.