It was while Jim Sperow was thrashing on the pavement with the bank-robbery suspect, grappling for the gunman's loaded .44 Magnum revolver, that a thought occurred to him.

"I was hoping those guys would be proud of me," the 25-year-old printer said later."Those guys" are two San Francisco cops, Inspector Carl Klotz and retired Detective John Fotinos, who took the one-time gang member under their wing as a teenager, got him into a trade school and helped straighten out his troubled life.

And, yes, they are very proud of Sperow.

Sperow is being hailed by police as a hero after he chased down an armed bank-robbery suspect Tuesday morning, tackled him in an alley, then disarmed him and held him until police arrived.

His brave action and the description he provided of another suspect resulted in the arrest of two men and the recovery of $52,527 taken in the holdup. Authorities are now investigating the men in connection with a string of well-planned robberies in the area.

"He (perow) did a great job," said Officer Michael Jameson, who arrested the suspect. "But I don't know if I would have done the same thing. That was a pretty damn big gun."

Sperow had just taken a break from his print shop job and walked around the corner to the Wells Fargo branch to cover a check for groceries his wife wrote the previous night.

"I was waiting in line when a guy jumped over the counter yelling: `It's a holdup! It's a holdup!' " he said. "I said to myself: `Wow! Here we go.' "

As Sperow and the other customers watched, the tellers stepped back from their cages while the suspect, identified by police as Robert Michael Linsey, 41, of San Martin, Calif., scooped handfuls of money from the cash drawers into a gray bag. Another suspect, later identified by police as Joe Dewayne Duke, 41, stood by the door brandishing a fully loaded .44-caliber Magnum revolver.

When the two men ran out of the bank, Sperow didn't hesitate to go after them. He tackled Duke from behind and brought him to the ground with a hard punch to the head.

"I figured it was better to go for the guy with the gun," he said. "If I went for the guy with the money I might have gotten shot."

A crowd gathered as he and Duke struggled on the ground, but no one offered to help. Sperow, who has a wife and 11/2-year-old daughter, remembers thinking that this was not a good time for bullets to start flying.

Sperow managed to wrestle the gun away, punched Duke in the face with his fist, then bashed him in the head with the revolver, effectively ending the fight.

"When the people standing around saw the .44 Magnum, they all screamed and dove for cover," he said. "It was like something out of a Clint Eastwood movie."

Police pulled up shortly afterward and pinned both Sperow and Duke to the ground until bank employees identified Sperow as the witness. About four hours later, police arrested Linsey in Alameda.

An hour after his wrestling match, still buzzing from the adrenaline surge, Sperow stood in the alley, recalling less heroic days.

"Those two cops straightened me out and got me on the right track," he said. "I was just glad I could do something to try to pay them back."

Growing up without a father at home, he drifted into trouble as a teenager, Sperow said. He said he had stolen automobiles and brought home straight F's on his report cards. He still bears the tattoos from his position as sergeant-at-arms for the Rebel Rousers, a teen gang. "I was a punk, someone who was on the wrong track," Sperow said.

At age 14 he witnessed a drugstore robbery in which a private police officer was shot and killed. In the aftermath of the case, the two homicide investigators, Klotz and Fotinos, took him under their wing.

Sperow wanted more than anything to become a printer, but the trade schools took one look at his grades and rejected his application. Fotinos and Klotz made a few phone calls and got him accepted at the John O'Connell School of Technology, where he earned his degree.

Later, they intervened when Sperow was unable to get a driver's license because of his record.

"He was a good kid, just someone who was having a few problems. What kids don't these days?" said Fotinos.