The man he tried to kill was also a former constable.

He was dismissed on February 19 after being accused in two separate cases of molestation and rape.

Constable Sudip Banerjee, posted with the South Traffic Guard, was arrested from Barrackpur in North 24 Parganas on Saturday night.

He was produced before the Serampore Sub-divisional Magistrate which remanded him in police custody for seven days.

The police said Sudip wanted to eliminate Gopal Das (33), a former constable posted at the Baranagar police station, so that he could marry his wife.

According to the police, two contract killers allegedly hired by Sudip had shot at Das, injuring him, on March 9. Gopal was standing in front of his cyber café at Kanaipur in Hooghly when the incident occurred. The killers had also hurled a bomb at him, which left a vegetable vendor, Musha Ali (36), injured.

The police said they could not find any motive behind the attack initially. A few days ago, they got a tip-off about Sudip's affair with Gopal's wife and started investigating his role.

Officers said Sudip had first met Gopal's wife in a private get-together in 2007. Their friendship soon grew into a serious relationship, they added.

When Gopal came to know about them, he allegedly threatened the two with dire consequences. He had allegedly warned Sudip that he would report the matter to his seniors.

The police suspect that Sudip got worried about his reputation and planned to eliminate Gopal, with the help of his wife.