The app cab owner arrested for allegedly stabbing a woman in his vehicle had placed an order for a knife with a shop in Bishnupur in South 24-Parganas during the lockdown, police said on Sunday.

The accused — Shiv Shankar Manna, 35 — had specified to the shop owner that the knife, which is believed to be the murder weapon, should be bigger than standard vegetable knives and forced him to work during the lockdown to make it.

The fact that Manna had felt the need for a big knife has made the police suspect that he had been plotting the murder for several weeks.

The police have recovered the knife from the Maruti Alto in which Manna had allegedly killed neighbour Lakshmi Das, apparently to avoid repaying the Rs 30,000 he had borrowed from her.

“The knife was made on order placed by the accused. We will talk to the shop owner who supplied the knife,” said an officer at the city police headquarters in Lalbazar.

Lakshmi, 45, mother of two, worked as a help at a house in Mudiali. Manna offered her a lift on Friday afternoon. According to Manna’s statement, he lost his cool when she asked him about repayment and tried in vain to strangle her. He then stabbed her neck multiple times to ensure her death.

“He claimed he had been keeping the knife inside the car for his safety because he often made night trips. He said he would at times feel insecure on those trips,” an officer said.

However, police said they were yet to get any satisfactory answer as to why he had to procure a specially ordered knife during the lockdown, when the app cab service was suspended.

The police have learned that Manna had purchased three cars with bank loans, which he was finding difficult to repay.

Manna’s wife Pinky had told The Telegraph that recovery agents visited their home multiple times for repayment.