A top official in the Wisconsin State Patrol and a spokesman for Walker said the increased costs were mostly because of death threats against the Republican governor and lieutenant governor and their families. But Walker’s office also acknowledged that other factors like the increased security for Walker’s two homes and younger family played a role.

The costs of the governor’s security detail totaled $611,400 over the 10 months from Walker’s election in November 2010 to the end of August of this year, according to documents released to the Journal Sentinel under the state’s open records law. That was more than twice as much as the $259,900 that it cost to protect then Democratic Gov. Jim Doyle over the comparable 10-month period from November 2009 to August 2010.

David Erwin, a captain in the State Patrol and the head of the unit that protects the governor, said the threats against Walker have reached a new level. State officials declined to discuss those threats or the governor’s security in any detail because they said it might put him at risk.