Sanjeevan, who is from Bahau, had alleged several times that he received death threats due supposedly to his revelations of police corruption.
Asked if the attack could be over Sanjeevan's allegation of rampant gambling activities in the Jelebu district, SAC Osman said the police would investigate all angles.
"The motive of the attack could be revenge but we are continuing with our probe," he said adding the shooting was being investigated for attempted murder.
In January, Sanjeevan alleged that a policeman from the Jelebu police headquarters had threatened to shoot him after he informed Bukit Aman of illegal gambling outlets operating in the area.
SAC Osman said: "We did investigate the Jelebu case as the victim lodged a police report and then referred the case to the DPP. However, the case has been NFAed (no further action)."
He said Sanjeevan had been informed of the outcome of the case.
SAC Osman added that Sanjeevan was certain the man who issued the death threat was a police officer intent on protecting the illegal gambling outlets which had been operating for two years.
On a statement by former Inspector-General of Police Tan Sri Musa Hassan that the shooting could be due to Sanjeevan's expose on police misconduct, SAC Osman said police welcomed leads.
"Sanjeevan did report this to Bukit Aman previously but we need more information before we can act.
"The problem is that apart from the Jelebu case, Sanjeevan was not specific with his allegations," he said.