Kader Khan, prime accused in the Park Street gang-rape case, was arrested on Thursday in Ghaziabad in Uttar Pradesh by a special team of Kolkata Police, according to a PTI report.
An accomplice of Khan's, named Ali, who had helped him stay hidden, was also arrested.
Khan had been hiding in Bangladesh and, after running out of cash, returned to Delhi through Nepal.
According to reports, the arrested men will be sent to Kolkata on transit remand and will produced in front of a local court on Saturday.
Khan was the main accused in the Park Street gang-rape case, in which woman's rights activist Suzette Jordan was sexually assaulted by five men and raped in a moving car, in February 2012.
In December 2015, three of the accused — Naser Khan, Ruman Khan and Sumit Bajaj — were held guilty and sentenced to 10 years imprisonment.
Jordan, a mother of two, was offered a lift by the men after she came out of a nightclub in Park Street.
Unusually for a rape survivor, Jordan revealed her identity and became an anti-rape campaigner. She died on 13 March 2015 of multi-organ failure after being diagnosed with encephalitis.
"We had information that Khan had returned to the country and was having regular interaction with his family members in Kolkata over phone," a police officer told PTI. "We started tracking their numbers and found that calls from a particular number from Ghaziabad were made. We started tracking it and found that it was Khan's."