JANESVILLE, Wis.- The estranged stepfather of a Wisconsin man suspected of stealing guns and threatening attacks in an anti-government manifesto for the White House is desperate for the fugitive to surrender.

Don McLean repeatedly pleaded in an interview with The Associated Press Tuesday for Joseph Jakubowski to give himself up, saying he and his mother "would rather have him alive."

Authorities have been searching for Jakubowski since April 4, when authorities believe he stole 18 firearms from a gun store in Janesville, Wisconsin, about 70 miles southwest of Milwaukee.

Rock County Sheriff Robert Spoden has said Jakubowski threatened to attack schools and public officials in the 161-page manifesto that he mailed to President Donald Trump. That manifesto allegedly made its way to the White House on Tuesday.

More than 150 state and federal law enforcement officers are searching for the 32-year-old man.

Investigators released photos of Jakubowski's tattoos and cautioned that he may have changed his appearance. 

The FBI has offered a $20,000 reward for information leading to the arrest of Jakubowski, who is considered "armed and dangerous."

Authorities say they have received more than 500 tips, including 150 on Monday alone.