So for those who don’t know
That is Terry Kath, he was the lead guitarist and a singer in the band Chicago. One day the band was partying at the home of a road crew member’s house named Don Johnson. The party had ended and it was just Kath and Johnson, Kath took out his pistol and started twirling it. Johnson told him to stop playing with his weapon then Kath told him that the gun wasn’t even loaded then he proceeded to put the gun up to his head and pull the trigger. The gun WAS loaded and he died instantly.
I couldn’t find much more information about Don Johnson, but considering he was the only person that witnessed it, the police were most likely suspicious that he might have killed Kath and probably investigated him for the murder of Terry Kath.