The former immigration police chief on Wednesday linked the gunshots fired into his car on Monday to his opposition to a 2 billion baht contract for biometrics equipment to screen passengers at major airports.
Surachet Hakparn handed over documents relating to the biometric project to interrogators while being questioned at Bang Rak police station.
The former flamboyant police officer, better known as Big Joke, told reporters that he viewed his attempt to block the project as the only possible motive for the attack on his SUV on Monday night.
Pol Lt Gen Surachate had earlier urged national police chief Chakthip Chaijinda, in a written statement, to consider cancelling the project when he was still the immigration police commissioner last year.
The 2 billion baht project involved the purchase of biometric equipment to scan the faces and fingerprints of visitors and residents going through major airports. He cited the long delay and questioned the equipment's efficiency as among the reasons to end the contract.
Sittra Biabangkerd, an independent lawyer, has asked the National Anti-Corruption Commission to look into the project.
Pol Lt Gen Surachate denied any connection with Mr Sittra's move for a graft investigation.
After Big Joke was forced out of the police circle into a civilian position as adviser to the Prime Minister's Office last year, his successor, Pol Lt Gen Sompong Chingduang, placed stress on being fair to the contractor.
The new immigration police chief has even praised the biometric system on more than one occasion, pointing out how it had identified suspects passing through airports, and they were then arrested.
A gunman fired eight shots into the passenger-side doors of the Lexus SUV that Pol Lt Gen Surachate drove and left parked in a soi outside a massage parlour in Bang Rak district on Monday night. Police recovered two bullets for forensic examination, and believed the rest were in the vehicle.
His career path soared, overshadowing more senior officers, when Deputy Prime Minister Prawit Wongsuwon was in charge of police affairs during the junta regime from 2014-2019.
In an interview on the Inside Thailand programme on Mcot TV on Wednesday, Pol Lt Gen Surachate said he exited his police career with no personal grudge towards other officers. "I am no longer a police officer. I left my police career behind with no personal conflicts," he said.
At Bang Rak police station, he said Pol Gen Chakthip should accept responsibility if police could not find the men who shot at his car. The case was in its third day, but police said they still had no leads on finding those responsible, he added.
Metropolitan Police Bureau chief Pol Lt Gen Pakkapong Pongpetra said the placement of the bullet holes showed that the attackers intended to threaten Big Joke, not to kill him.
Lawyer Sittra posted a Facebook message on Tuesday saying the shooting was linked to the NACC's intention to call Pol Lt Gen Surachate in to provide more information about the biometrics project, as part of the graft investigation.