Santosh Kumar Singh, an Army jawan who allegedly shot dead his colleague Rinkesh near Danapur cantonment on Sunday night, was not just his friend but also his guide.

Two years back when Rinkesh joined the Army and was undergoing training at the Bihar Regimental Centre (BRC) in Danapur, it was Santosh who provided him training.

It was during the training session that bonhomie set in. Rinkesh started considering Santosh his guide and mentor. 'The two jawans were not just colleagues but also good friends,' Patna superintendent of police (SP) West, Ravindra Kumar, said quoting Rinkesh's family sources.

'There were several photographs of both Santosh and Rinkesh together. As Rinkesh considered Santosh his mentor, he took suggestions and advice from him for every problem he faced.'

Though Santosh (30) was posted in Arunachal Pradesh, his family stayed in Danapur. So Santosh, who had befriended Rinkesh (22), an Ara resident, used to meet him whenever he came to Patna on leave.

The police said Santosh was reportedly pressuring Rinkesh to marry his cousin. This could have led to arguments.

'After shooting Rinkesh, Santosh tried various ways to commit suicide, such as hanging from the ceiling and trying to cut his vein with a knife before finally deciding to thrust the barrel of his rifle in his mouth and pull the trigger,' SP Ravindra said. The police recovered two pieces of rope and a knife from the site.

'Prima facie, it appears Santosh killed his friend in a fit of anger and then went into shock,' said an official looking into the investigation. 'Maybe he tried to hang himself with a rope, but the rope broke. Also, he might have tried to cut his vein with a knife but could not muster the courage. Lastly, he shot himself.'

The official said there was 20-minute difference between the two deaths. 'The exact timing of death can be ascertained only after the post-mortem report is available, but Santosh tried various ways to kill himself during these 20 minutes.'

The police official also said: 'Santosh wanted Rinkesh to marry his cousin and the two families had even exchanged photographs in this regard. Rinkesh even used to talk to the girl, but Rinkesh's parents later decided not to proceed with the proposal. This could have made Santosh furious and made him execute a plan to kill his friend.'

Patna police have constituted teams that will probe the case after gathering information about the two jawans from their family members and army jawans.

Meanwhile, police have lodged a case of suicide and murder in this connection.