Updated

Authorities are investigating a letter threatening Easter attacks on churches in Wisconsin purportedly sent by the subject of a manhunt accused of stealing weapons and sending a rambling manifesto to the White House.

The letter mailed by someone claiming to be Joseph Jakubowski threatens unspecified violence on Sunday at churches in the Sussex area, about 25 miles northwest of Milwaukee. Rock County sheriff's officials are trying to determine if the letter is authentic.

Jakubowski is accused of stealing 18 guns from a store near Janesville April 4. Officials believe the 32-year-old man also wrote an anti-government manifesto indicating his dislike for religion and a desire to carry out unspecified attacks.

Meanwhile, Gov. Scott Walker has canceled his annual Easter egg hunt scheduled for Saturday while Jakubowski remains at large.