The sheriff's office and Janesville police increased patrols near churches Sunday, although investigators said there was no specific threat.
Police believe Jakubowski stole a large quantity of handguns and rifles form the store in Janesville, 70 miles southwest of Milwaukee Tuesday night. Friends told investigators from the Rock County Sheriff's Department that Jakubowski made a series of politically-related threats, and said he was going to steal weapons and attack schools.
On April 6, elders of Bethlehem Lutheran Church in Sun Prairie reported a suspicious man matching Jakubowski's description who went to them and asked questions about church services and practices, including inquiries about turning people away. They say Jakubowski is a suspect in both incidents.
A nationwide manhunt is underway in the United States for an "armed and highly dangerous" suspect who robbed 16 high-end guns and may be plotting an act of mass violence targeting government officials.
Police discovered that Jakubowski burned his auto and then disappeared after the store thefts.
Federal authorities say Joseph Jakubowski, 32, may be planning an act of mass violence against a church or religious group, ABC News reports.
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"When you look at his document that he wrote, it's really a long list of injustices he believes the government and society and the upper class have put forward onto the rest of the citizens", Spoden said. Therefore, Jakubowski is considered risky and should not be approached, if observed.
Jakubowski has been on the run since Tuesday and police authorities have kept a close watch on any tips they have found in order to track him down.
Authorities identified the person who filmed the video as an associate of Jakubowski and a person of interest in the investigation, Rock County Sheriff Robert Spoden told reporters Sunday.
Police today also released a social media video that they said depicts Jakubowski's sending a package to Trump.
Police said in a press release Jakubowski had been "highly agitated recently regarding a variety of political issues". The following day, Janesville and Milton public schools were closed, as were the University of Wisconsin at Rock County and Blackhawk Technical College.
Jakubowski is described as 5-foot-10 and 200 pounds with green eyes and brown hair.