Crime doesn't pay, and neither does stopping one.

A Seattle bank teller learned that lesson the hard way last week when he thwarted a would-be robbery — and got fired for bucking company policy.

Jim Nicholson was working at a Key Bank branch on Tuesdaywhen a man wearing a beanie cap, dark clothing and sunglasses entered the bank and demanded money. That's when instinct overwhelmed him.

"They tell us that we're just supposed to comply, but my instincts kicked in and I did what's best to stop the guy," the 30-year-old Nicholson told The Seattle Times. "I thought if I let him go he would rob more banks and cause more problems."

Rather than comply with the robber's demands, Nicholson tossed his bag to the floor, lunged at the suspect and demanded to see a weapon.

"My intent was to grab his glasses off his face, or him," Nicholson told the paper.

The man ran, and Nicholson chased him for several blocks before knocking him down with help from a passerby. Nicholson then held the suspect, Aaron J. Sloan, 29, until police arrived.

Nicholson's reward? Two days after the failed heist, he was fired.

Key Bank spokeswoman Anne Foster declined to comment on his termination, but she said protecting the safety of employees and clients was the bank's top priority.

"Our policies and procedures are in the best interests of public safety and are consistent with industry standards," Foster said in a statement to FOXNews.com on Monday. "Money, which is insured, can be replaced. Lives cannot."

Seattle Police Sgt. Sean Whitcomb echoed Foster's sentiment.

"It really doesn't matter if you're a bank teller or a citizen walking down the street. Generally speaking, it's best to be a good witness," Whitcomb told FOXNews.com. "And quite honestly, this is also true for people who are off-duty police officers too."

In the event of a crime in progress, Whitcomb urged citizens to get a description of the suspect, especially of his or her clothing.

"It's best to help the people who are on duty, to help them catch the person," he said. "There's just so many bad people out there and there's so many variables."

Just days before the bank incident, Whitcomb said a clerk at a local convenience store in Seattle was killed when he tried to stop an armed robbery in progress.

"Would that have happened if the clerk just let the guy take the cash? I don't know," Whitcomb said.

Sloan, 29, has a lengthy criminal history, including convictions for theft and robbery. He remains jailed on $1 million bail, officials at the King County Prosecuting Attorney's Office said. Charges related to the attempted robbery have not yet been filed.

Nicholson, who could not be reached for comment Monday, told The Seattle Times it wasn't the first time he had pursued a thief, citing past experiences with shoplifters at retail jobs in New York and California.

"It's something I almost look forward to," Nicholson said. "It's a thrill and I'm an adrenaline-junkie person. It's the pursuit."

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