The stepfather of two girls whose bodies were found at Park Circus station and Dhakuria bridge a year ago has been arrested in Mumbai for the twin murders.

A team from Calcutta police went to Mumbai on Monday to seek the custody of Istiyak Khan, 27.

The bodies of seven-year-old Aliya and 11-year-old Sabiya were found dumped on January 24 and 25 last year.

Aliya's body was found in a jute bag at Park Circus station on January 24. The next day, sister Sabiya's body was carried in the boot of a taxi and dumped in a garbage vat at Dhakuria in broad daylight.

Some residents saw a man get off the taxi, take a bag out of the boot with help from the cabbie and dump it in the vat before walking away. Ragpickers later found a girl's body, in a yellow salwar kameez, was stuffed inside.

Calcutta police, who were clueless about the identity of the girls till recently, came to know about Istiyak Khan only last week, when an officer of Mumbai police contacted them and sought confirmation about the twin murders.

Sources in Mumbai police said someone had reported to them about the disappearance of Khan, wife Abida Khatoon, 40, and the two girls from Dharavi, in central Mumbai, where the accused worked in a in a purse-making unit.

"When he returned to Dharavi recently without his family, Mumbai police picked him up and interrogated him. He apparently broke down and confessed to having killed his wife and the two stepdaughters," an officer said.

According to Mumbai police, Khan, a native of Banda in Uttar Pradesh, met Khatoon, a widow who owned a room at Dharavi, in Mumbai.

He befriended her, promised to marry her and convinced her to sell her room in Dharavi.

Eyeing the Rs 9 lakh earned from the sale of the property, Khan took the family to Calcutta where he married Khatoon.

"Khatoon started insisting that Khan take her to Banda. But he kept refusing since he already had a wife there and did not want his family to know about Khatoon and her two daughters," said Dhananjay Kulkarni, a deputy commissioner of Mumbai police.

In January last year, Khan told Khatoon that he would be taking her to Banda but strangled her on their way. He dumped her body in a farm at Lalauli, in Fatehpur district in Uttar Pradesh, before proceeding to Banda.

"He soon returned to Calcutta and told the girls that he had dropped their mother home and will take them there, too," Kulkarni said.

He then killed the girls and disposed of their bodies.