MINNEAPOLIS, Minnesota - July 22, 2009 - Tyler Heilman, 24, had just arrived home in Kasota, Minnesota, after a day's swimming with friends when he was accosted by Todd Waldron, a sheriff's deputy, who had been following him in an unmarked car.

As the pair got into a scuffle, friends of Heilman insisted it was not clear that Waldron was a police officer when he asked to see the other man's driver license.

According to the friends, the two men got into an argument and ended up wrestling on the ground. As Heilman got up, he finally saw the police badge on Deputy Waldron's belt, said Kris Hoehn.

"Then came the gunshots, just as my buddy's hands were going up," he said. "It was too late this officer flew up off the ground, gun in hand. If we would have known he was a cop, none of this would've happened."

Investigators believe the policeman fired four shots, two of them hitting Heilman in the chest.

They said the officer had seen Heilman driving erratically - at one point taking his car off the road and mounting an embankment - and had followed him.

Waldron, 37, has been placed on standard paid administrative leave pending an investigation.

Friends of Heilman, who had a string of convictions for minor crimes, have staged a vigil outside the local police station and say they will remain there until police answer their questions about the killing.

"This ain't right," said Heilman's father, Mark. "I think the cop just freaked ... Why didn't he just say 'Freeze' or something? Or shoot him in the leg? He shot to kill ... I think he just flipped."