Police in the Indian capital, Delhi, say they will investigate claims of a conspiracy to pervert justice in a high profile murder case.
Eyewitnesses said Ms Lal was shot for refusing to serve a drink
There has been uproar ever since the acquittal last month of those accused of the 1999 killing of a model, Jessica Lal, in a Delhi bar.
Manu Sharma, son of a Congress party minister in Haryana state, Vinod Sharma, was the main accused.
Delhi police say they will appeal against the acquittals.
Jessica Lal was shot dead in April 1999 in the Tamarind Court restaurant, owned by socialite Bina Ramani.
She was working there as a barmaid. Witnesses in the crowded bar said Manu Sharma shot her after she refused to serve him.
The eyewitnesses later retracted their statements and the judge said the case presented by the prosecution had several loopholes.
The charge sheet that the Delhi police originally submitted to the court said there were many people in the restaurant at the time of shooting.
Delhi police commissioner KK Paul told reporters on Monday that a special team had been set up to examine criticism of the investigation into Lal's murder.
Anger over the acquittals continues
He said that the police had lodged a case against "unnamed persons" in the case for "destruction of, tampering with and fabrication of evidence", the PTI news agency quotes Mr Paul as saying.
The investigation would also examine whether there was a "common intention to commit the crime and conspiracy charge", PTI reports.
Mr Paul did not specify if the "unnamed persons" were police officers or other people connected to the case, or both.
Mr Paul said the Delhi police had analysed last month's acquittals and the police would also file a high court appeal against the judgement soon.
"There were certain aspects which would form the basis for going to the higher court... we will wait for the orders of the high court."
The court acquitted all nine accused citing insufficient evidence.
This triggered off angry public protests, nationwide SMS campaigns and candlelight vigils at the place where Lal died.
Legal experts have been scathing about the way the case has handled. Many have asked how the police failed to convict anyone of the killing when so many people in the bar were witnesses.