A 25-year-old man from Karnataka, wanted in at least 13 cities for allegedly stealing wallets and mobile phones, was arrested from Ernakulam in Kerala by the Bidhannagar city police on Sunday.

Kurapati Ajay allegedly used stolen credit and debit cards to purchase gold jewellery and new phones across the country over the past few years, police said.

His sophisticated operation involved befriending hotel guests, robbing them, and then returning the stolen items once he had completed fraudulent transactions — a tactic that delayed victims from reporting the crimes.

Ajay would use a mobile phone to book accommodation at hotels or guesthouses and hire bike cabs to reach his destinations. Once there, he would befriend other guests before robbing them, police said.

“He would mandatorily steal his target’s mobile phone along with the (credit or debit) cards so he could access the phone when an OTP was generated while making an online purchase,” said Sonawane Kuldip Suresh, deputy commissioner (detective department) of the Bidhannagar police.

Despite having studied only till Class XII, Ajay had done a course in ethical hacking, “which helped him immensely to dupe his targets,” the police said.

The Bidhannagar police began searching for Ajay in July after officers at the Bidhannagar East police station received a theft complaint from a visitor from Bihar staying at a guesthouse.

The guest reported the theft of a mobile phone, wallet, and laptop. During the investigation, police discovered that the credit card from his wallet had been used to buy gold jewellery from a reputable Calcutta jewellery showroom, purchase two mobile phones, including an iPhone, and transfer money to another person’s bank account.

“We started to search to find out if a similar modus operandi had been used by anyone else in the country. To our surprise, we found that a similar crime pattern had been reported in many large cities,” Sonawane Kuldip said.

In Calcutta, he had assumed the identity of one “Sai Krishna.”

In all the reported cases, the accused had used stolen ATM or credit cards to purchase gold and new mobile phones and transfer money. Once the transactions were complete, he would return the stolen items to their owners.

Investigators are still trying to figure out why he would take the risk of returning the stolen items to his victims. They expect to learn more, including how he returned the items, when they question him.

Police said they have located at least eight FIRs against Ajay and at least five cases on the National Cyber Crime portal. “Our preliminary inquiry has revealed that he is wanted in Uttarakhand, Rajasthan, Kerala, Telangana, Mumbai, and Ranchi, to mention a few,” an officer said.

According to police records, Ajay was previously arrested in Gangtok and Bengaluru. “In both cases, he was either purchasing gold with a stolen card or making an illegal transaction using the cards when police traced him,” an officer said.

Police said Ajay was adept at concealing his trail. He allegedly used at least 38 SIM cards — destroying each one after use —and changed his phone sets regularly.

Ajay used forged Aadhaar cards to purchase new phones, making it “next to impossible to track him with so many identities,” an officer said.

Police had to scan through a web of 98 mobile connections that had been used at various times to commit fraud or make fraudulent transactions. Ajay would sell the newly purchased phones on online trading portals, police said.

He will be brought to Calcutta on transit remand.