They often do it in the movies — a cop and a criminal on parole who love to hate one another but are forced to join hands to catch a fugitive. They succeed in their mission and, if the scriptwriter wants a happy ending, even become friends for life.

Alas, no such luck for Calcutta police, whose attempt at setting a thief to catch a thief ended up being little more than a paid holiday in Mumbai for the dodgy informer they chose for the task.

The police’s litany of embarrassment actually began in February, when Mohammad Sabir, alias Chand, fled the Taltala police station lock-up. Sabir, arrested for a theft on Ripon Street, had asked for water when a constable opened the lock-up to serve him dinner and pounced on him when he turned around to fetch a bottle. Sabir then ran out of the police station.

The constable and his colleagues did chase the undertrial for a few hundred metres, but lost sight of him once he entered one of the narrow bylanes in the area.

The police have since used the services of three informers with criminal antecedents to trace Sabir, but without any success. The first two were sent to Ghutiari Sharif, in South 24-Parganas, and Canning. The third went to Mumbai recently and stayed there for five days.

“Sabir had stayed in Mumbai for several years and we have a hunch he is hiding there. We spent Rs 2,550 on our informer’s train fare, food and accommodation in Mumbai for five days, but he came back empty-handed,” Tarapada Dutta, the officer-in-charge of Taltala police station, said.

Investigators are now banking on “some Calcutta youths who work in Mumbai” to gather data on Sabir’s whereabouts.

“We have spent quite a packet on sources who might help us nab him. It has become a prestige issue for us. We have to arrest him,” Dutta said.

Sabir’s escape from lock-up had been kept under wraps for nearly a week after the incident occurred.