Mumbai/New Delhi: One of the two arms suppliers in the firing case outside actor Salman Khan’s house died by suicide today while in police custody, sources said.Anuj Thapan, 32, who was arrested from Punjab on April 26, went to a toilet attached to the police lock-up at 11 am and took the extreme step, sources said.He stayed with 10 other inmates in the lock-up, guarded by four-five policemen.He and another accused, Sonu Subhash Chander, allegedly gave the weapons used in firing outside the ‘Tiger Zinda Hai’ actor’s Mumbai home on April 14.What drove Anuj Thapan to suicide is under investigation, sources said.Former Maharashtra senior police officer PK Jain told NDTV any death in a lock-up is reported as a murder case. “All the policemen in the police station will be questioned by the CID (Criminal Investigation Department),” Mr Jain said.The former top cop said police usually ensure lock-ups are checked for any object that could be used by a person to die by suicide.