Gandhi took to Twitter and wrote: "The best way to silence terrorist Deputy Superintendent of Police Davinder is to hand the case to the NIA. The NIA is headed by another Modi - YC who investigated the Gujarat riots and the Haren Pandya assassination case.
"In YC's care, the case is as good as dead. #WhoWantsTerroristDavinderSilenced and why?"
The NIA chief is a 1984-batch officer of the Assam-Meghalaya cadre and previously served in the Central Bureau of Investigation.
He was part of a Supreme Court-appointed Special Investigation Team that probed then Gujarat Chief Minister Narendra Modi's alleged role in the 2002 Gujarat riots.
Speaking to the media at the party headquarters here, Congress spokesperson Supriya Srinate said that the National Investigation Agency's own role has been under suspicion as far as cases of BJP's Bhopal MP Pragya Thakur and Swami Aseemanand are concerned.
"I really think it is incumbent on the (central) government to come on record, to clarify the role of Singh to ensure that any probe is above board," she said.
She said that the suspended DSP was not just another police official in J&K, but "somebody responsible for the security of foreign envoys". On January 9 - three days before he was arrested in the company of two alleged militants - the police officer was responsible for the security of 17 foreign envoys who visited the Valley, the Congress leader claimed.
"Singh was not just an important official he had the confidence of the government. He was I want to put it on record DSP (DR) in Pulwama region where a terror attack occurred on February 14 last year, in which 40 innocent CRPF troopers lost their lives," she said.
The Congress leader pointed out that the country was still haunted by a question regarding the huge quantity of RDX used in the attack.
Srinate said that Singh had faced three FIRs in extortion cases, apart from the fact that his name cropped up in the Parliament attack case of 2001.
"Why is the government silent? Its conspicuous silence raises more uncomfortable questions.
"Whom did Singh report to? Was he a mere pawn in the larger scheme of things? Why is the government, the National Security Advisor (Ajit Doval), the Home Minister (Amit Shah) or the Prime Minister (Narendra Modi) silent?" she questioned.
( With inputs from IANS )