You saw a random unidentified player approaching, After the player you were attempting to kidnap said he forgot his wallet at home you basically instantly shot him dead, How is this in any way allowed or the right way to handle a situation?
Put yourself in the kidnapped players shoes, Would you like it if someone came to you with poor roleplay(not wearing a mask, Robbing next to a PD) And executed you because they wanted to have a little roleplay?
There is many ways you could have handled the situation better, Like drag him to the boot of your vehicle with scarce from your weapon. Take him to another location and get him to give up any goods he has, Or better yet you could simply SEARCH his body for his wallet, Maybe he was bluffing?