Ten years ago a bank robbery was committed by Fast Frankie and one of his accomplices. To this day his accomplice is unknown. Fast Frankie had served 5 years in jail, refusing to give up his accomplice, and the location of the missing cash and jewels. Fast Frankie had deliberately not told his accomplice where the money and gold was hidden - he didn't want to get out of jail and find it all spent.

But now, Fast Frankie lay dying. He had been shot by Detective Sing (in the line of duty). Detective Sing sat next to him, waiting for the ambulance that had been called.

"Tell my son," Frankie whispered.

"Yes?" said Detective Sing.

Fast Frankie tried again "Tell Johnny...the money...it's in the West Bank..."

Frankie lay down, his breathing stilled, and he died.
Detective Sing got to his feet, and he ordered that all his men start searching West Bank for the missing money. He suspected that Johnny was the missing accomplice, and that Fast Frankie had just told him where he'd stashed their spoils.

The next day the officers returned to Detective Sing and said that no one at the West Bank could find any trace of the missing money or gold. Detective Sing thanked them, and went to contact Johnny, to see whether he could help them. At the interview, Johnny asked whether Frankie had had any last words for him. Detective Sing told Johnny what Fast Frankie had told him. Johnny thanked Detective Sing, and shortly after left to go make arrangements for the funeral.

The next day Detective Sing had another interview with Johnny. A sparkle of gold caught Detective Sing's attention.

"Where did you get that gold watch?" he demanded.

"My father left it to me," Johnny smirked.

On the pretext of getting a cup of coffee, Detective Sing ordered some of his men to go have a look at Fast Frankie's property (no, not to search it, that would be illegal without a search warrant). As the police officers crossed the bridge to get to Frankie's house, they saw something which was enough to have Johnny arrested as the missing accomplice. What was it?