The man who made a bomb threat against the Natrona County Sheriff's office on Tuesday grew up in Jackson, where he had a long history of petty criminal offenses, a Teton County Sheriff's officer said Thursday.

"We don't know obviously how and why he is picking the targets he is," Detective Sgt. Todd Stanyon said.

"There doesn't really seem to be a rational pattern, but obviously we're dealing with an irrational person," Stanyon said.

Kreighton Kilgore, 33, allegedly called the dispatch centers of Natrona and Teton counties to directly threaten their respective sheriff's departments, he said.

But Stanyon said the public need not be worried. "His threats aren't credible."

Natrona County Sheriff's spokesman Sgt. Aaron Shatto declined to comment specifically about Kilgore, but did say the office is looking at a person of interest.

In Teton County, Stanyon said their Tuesday incident was not their first encounter with him.

Kilgore made two threats in Jackson on Jan. 21, the Jackson Police Department investigated, identified Kilgore as a suspect, and issued a warrant for him for making terroristic threats, Stanyon said. Kilgore also has an outstanding warrant from 2006.

"It quieted down for a little a bit, and then calls started coming in to other agencies and other areas," he said. Those other areas included Natrona County and Garfield County, Colo.

"The information they had led back to the same suspect we have here," Stayon said.

Kilgore grew up in Jackson, and he's had a long history with local law enforcement with petty crimes such as shoplifting, Stanyon said.

Currently he's a transient, his whereabouts are unknown but he's probably in the southwest somewhere, he said.

The Federal Bureau of Investigation also is looking at the case, Stanyon said.

There is no substantial threats to public safety, he said.

"He has a history of making these kinds of threats, and also making just annoying phone calls, just kind of nonsensical rambling phone calls," Stanyon said. "He's never followed through on them."

But threats like these can affect the public, if for example they cause a hospital to be evacuated, or causes an emergency response to a particular area to look for a bomb, he said.