Hilary Duff's alleged 18-year-old stalker has been arrested and sources tell TMZ the bust occurred after the man threatened to kill Duff this weekend.

Manhattan Beach cops arrested Maksim Miakovsky, an 18-year-old Russian emigre, at a Residence Inn last Friday. He was booked on charges of making criminal threats and stalking.

TMZ first reported last month that Duff and her boyfriend, Joel Madden, were terrified that Miakovsky would do harm to them. Duff and Madden asked for a restraining order, alleging that Miakovsky

"has stated his intention of 'removing' his 'enemies' (i.e., those who prevent him from being with her), has stated his intention of purchasing a weapon, and has threatened to kill himself and to engage in dramatic actions to get her attention."

Sources tell TMZ that last Friday, a private investigator from Sunset Protective Services contacted Miakovsky at the Residence Inn and Miakovsky stated his intention of killing Duff on Sunday at an event she was scheduled to attend.

According to legal papers filed by Duff, Miakovsky came to the U.S. "for the sole purpose of meeting and becoming romantically involved with Ms. Duff."