Main accused Nazrul aka Nazu was arrested from Sealdah station while he was getting down from a local train late last evening.
A man believed to be the main accused in the sexual assault of a 72-year-old nun during an attack at a convent school in West Bengal last year has been arrested.
Nazrul, a 28-year-old Bangladeshi national, was arrested at the Sealdah railway station when he was getting off a local train last evening.
"Our sources informed us that Nazrul was trying to reach Kolkata. Working on the tip-off, our officers were waiting for him at Sealdah station and caught him when he was getting down from Bongaon local (suburban train)," said senior police officer Chittaranjan Nag.
The police suspect Nazrul had been hiding along the border with Bangladesh since the attack that triggered shock and anger across the country.
"He was hiding somewhere in the border areas of Bangladesh. Probably after he was chased by the police there, he sneaked past the border to get into India. He was trying to flee somewhere," said Mr Nag.
Six people have been arrested so far for the attack on March 14 at a church and convent school in Ranaghat, about 100 km from Kolkata. The attackers vandalized the school before breaking into the nuns' quarters, locking them in a room and raping one of them.
The nun needed surgery after the assault. The pace of investigations had led to anger against the Bengal police and government last year.