A St. Paul man allegedly plotted to murder his ex-wife, cobbled together a "hit list" of people he believed wronged him, drew diagrams of buildings, and carried a loaded gun and hundreds of rounds of ammunition in his car.

Michael J. Mangan, 42, was motivated by a bitter divorce, according to charges filed in Ramsey County District Court. He faces four counts of aggravated stalking and three counts of terroristic threats.

St. Paul police called Mangan on Oct. 3 to talk about an incident in which three of his ex-wife's car tires were flattened. "I have much bigger plans in place!" he "angrily yelled," according to the complaint. "God help any police officer who knocks on my door!"

Mangan was arrested on Oct. 4 during a traffic stop. Police found a loaded gun, "hundreds of rounds of ammunition," a boot knife and a gun-cleaning kit. A search of his home in the 1000 block of Avon Street yielded sealed letters addressed to 11 addresses or groups of addresses, which Mangan's girlfriend told police he had instructed her to send once he was "gone," the charges said.

According to the complaint: Mangan's sister and brother-in-law went to police because they feared him. Mangan's brother-in-law said that on Sept. 12 he was with Mangan at a library and Mangan said that he kept tabs on people who wronged him and that he carried a handgun. The brother-in-law saw papers diagraming the ex-wife's apartment complex and workplace. Mangan has four children with the woman, including three minors who live with her.

Mangan's sister and brother-in-law told police he was stalking them and some of the people on his list, which included a friend of the ex-wife's, two pastors, a court employee, an investigator at the Minnesota Department of Commerce and a sergeant.

St. Paul police stationed themselves in Mangan's neighborhood on Oct. 3 and observed his girlfriend scouting the area, the charges said. Officers returned the next day and saw the girlfriend leave, apparently dressed as a man, the charges allege. Mangan soon exited and drove away. He was stopped and arrested.

In his letters, Mangan told several people he would see them in hell.

"Your mother did this," he wrote in a letter to his children. "… I took the only action I had left in my power and that was to remove the problem."

Chao Xiong • 612-270-4708

Twitter: @ChaoStrib