Justice may be its own reward, but a District bank learned yesterday that if it offers monetary compensation as well, it had better pay up.

Ruth Ann Grant, 22, and Cindy Grant, 27, two sisters who helped foil a bank robbery near Dupont Circle in October, finally collected a $2,000 reward yesterday for their civic-mindedness -- just hours after their lawyer had filed suit in D.C. Superior Court claiming the bank had told the women they didn't deserve the reward.

The $2,000 reward is offered by the D.C. Bankers Association for information leading to the arrest and conviction of bank robbers. The Grants thought they were more than qualified to receive it.

While returning from lunch on Oct. 3, the women noticed a man walking out of a Connecticut Avenue NW branch of the First American Bank of Washington. They noticed him, the women say, because his briefcase was spewing red smoke -- a signal that he was carrying money that had been treated with red dye to show it was stolen.

"I'm sure a lot of people saw him, but most don't know what red smoke means," Ruth Ann, a paralegal, said yesterday. "He was walking nonchalantly . . . . We saw him take out a packet of red dye and drop it on the sidewalk."

The sisters trailed the man three blocks to a building, where he entered an elevator. They called the police, who arrived and made an arrest. The suspect, Vernon Maury, 58, subsequently pleaded guilty to robbery and was sentenced in U.S. District Court yesterday to 20 years in prison, pending further psychiatric and other court studies.

D.C. Police Chief Maurice Turner, in a letter to each sister, praised them for showing "great public spirit" and said their action had resulted in the arrest. He invited them to an awards presentation next year, where each will receive a certificate of appreciation and a $200 savings bond for helping the police.

But the initial response from the bank, according to the sisters, was substantially different.

"We never got a thank you, nothing," said Ruth Ann. She complained that the bank's chief of security, William Stoneman, was "rude" when she and her sister inquired about the reward, which was advertised by a sign in the bank's window.

"He said we weren't instrumental in getting the arrests and that we didn't deserve" the reward, she said. "He said we called the police too soon."

Stoneman, a member of the bankers association's protection and award committee, presented the reward check to the sisters at their attorney's office yesterday. He said he had recommended to the committee that the sisters be given the award and that he did not recall questioning or criticizing their actions after the robbery.

"The reward's paid," Stoneman said yesterday.

The sisters say that after their lawyer, Bruce J. Klores, inquired about the reward, the bank offered to give them $250 each, saying a decision about the $2,000 would have to be made by the association. After more delays, Ruth Ann said she and her sister filed their suit "because of the principle of the issue -- and because they were so rude to us."

The bank's sign, which the sisters took, offers the $2,000 reward "for information leading to the conviction for bank robbery." The sign's fine print explains that the bankers association committee pays the reward for information leading to the arrest, conviction and sentencing of a bank robber.

"Let us remember," the sign exhorts, "the greatest bulwark of public protection is the conscience of every citizen. Every citizen."

During the presentation of the reward check yesterday, Ruth Ann, who works in Klores' law office, said bank officials finally had thanked the sisters for their help.

"It's all over, and now we're having a glass of champagne to celebrate," she said. CAPTION: Picture, Cindy and Rugh Ann Grant show off a $2000 reward for foiling bank robbery. By Joel Richardson -- The Wasington Post