Mumbai, Jun 7 (IANS): The Mumbai Police suspect the possible involvement of the Lawrence Bishnoi gang in the death threat to Bollywood megastar Salman Khan and his father, writer Salim Khan, official sources said here on Tuesday.

As a precaution, Mumbai Police have beefed up security at the Khans' residence in Galaxy Apartments, Bandra West since Sunday while Joint Commissioner of Police Vishwas Nangre-Patil met Home Minister Dilip Walse-Patil to brief him on the case.

Nangre-Patil is understood to have briefed the Minister on the probe status including suspicion that the potential attackers may have conducted a discreet recce of the Khans' local movements and their residence.

A Mumbai Police team is likely to leave for New Delhi to question Bishnoi on his suspected involvement in the threats to the Khan family, especially since he had earlier vowed to kill Salman Khan after the actor was accused in the Black Buck poaching case of 1998 in Rajasthan.

In the current case, police said that Salim Khan, 87, was handed over an unsigned, hand-written threat letter by one unknown person on a bench where he normally rests after jogging at the Bandra Bandstand promenade, around 7.30 a.m. on Sunday.

It was addressed to him and his son Salman and facing something amiss, they immediately alerted their security to inform the police.

Taking serious cognisance, the Bandra police have lodged a first information report against unknown persons for issuing the death threats and launched their probe even as the Mumbai Police Crime Branch also started its own investigations.

The threat letter ends with a couple of initials including 'L.B.' which the police suspect refers to 'Lawrence Bishnoi' though the latter is understood to have denied any connection to the incident to the Delhi Police.