The Delhi Police on Wednesday said gangster Lawrence Bishnoi, currently in its custody, was the mastermind behind singer Sidhu Moosewala's murder, and that a close associate of the main shooter involved in the brutal killing in Punjab's Mansa last month had been arrested.

The police, however, did not divulge the details about the motive behind the killing of the popular singer and Congress leader and how Bishnoi conspired to execute the crime despite being lodged in the high-security Tihar Jail in the national capital.

Addressing a press conference, Special Commissioner of Police (Special Cell) H S Dhaliwal said that they have identified five more people involved in the murder case.

Dhaliwal said that Lawrence's relative Sachin Bishnoi's role in the killing has also emerged.

He said that Siddhesh Hiraman Kamle, alias Mahakal, has been arrested in Pune in a joint operation with the Maharashtra Police in a case under the Maharashtra Control of Organised Crime Act.

Mahakal, a close associate of the main shooter, is in 14-day custody of the Maharashtra Police, the special commissioner told reporters.

According to the police, Mahakal has committed a crime in Punjab's Moga district on the instance of Lawrence. Mahakal used to commit crime in coordination with main shooter of Moosewala's killing and Lawrence.

Earlier, Lawrence had told investigators that his gang's members, including Canada-based Goldy Brar, hatched a conspiracy and killed Moosewala.

Lawrence had also alleged that Moosewala was involved in the killing of Akali Dal youth leader Vikramjit Singh, alias Vicky Middukhera, on August 7 last year which led to a "rivalry" between him and the Punjabi singer.

Lawrence has been very uncooperative and has not yet disclosed the names of his gang members who were the real conspirators being the killing, officials had said.

"Bishnoi has been very uncooperative so far. But during interrogation, he accepted that he had a rivalry with Moosewala and claimed that his gang members killed the singer

"He has revealed that Goldy Brar was one of the gang members who conspired and executed the killing of Moosewala but has not yet disclosed the names of other associates who were the real conspirators and executioners of the killing," a police official had said.

Twenty-eight-year-old singer-politician Moosewala was shot dead by some unidentified assailants in Punjab's Mansa district on May 29, a day after the Punjab government curtailed his security cover.

The Mumbai Police's Crime Branch unit on Wednesday arrived in the national capital to question gangster Bishnoi in connection with a threat letter to screenplay writer Salim Khan and his son and Bollywood actor Salman Khan.

Dhaliwal refused to comment on the matter related to the threat letter.