Constable Rajkumar Saroj was rescued late last night from a house belonging to Tarikul Islam in North 24-Parganas district's Petrapole, a senior police officer said today.
The arrested person has been identified as Islam.
Saroj, a Khardah-resident, was kidnapped by a group of people when he was heading home from the Kolkata Police Headquarter at Lalbazar on August 3, the police said.
On getting a Rs ten lakh ransom call on August 3 night, Saroj's wife lodged a complaint with the Hare Street Police Station.
"We are still investigating how many people are involved in the case," the police officer said.