Acting on a tip off, a trap was laid and accused Sanjay Yadav, an autorickshaw driver, was nabbed from the city in the wee hours today, police said.
Earlier, police had arrested Sunny Singh (23) and Hari Dattani (25) in the case. According to police, Rajeev Choudhary (25) and his wife had been staying on rent in a shanty at Ganapath Patil Nagar slums in Borivali.
Singh, Dattani and Yadav had been observing the couple for the past few days and had even passed lewd remarks, following which the couple decided to change the house.
"The three youths barged into victim's house on Monday night thinking she was alone. Seeing her husband, the accused whipped out knives and threatened that he would be killed if he resisted," a police officer said.
The three gangraped the victim at knifepoint in front of her husband, police said.