Мафия 4. The Smell of Money.

Properties: 50% protection against attacks (if it triggers, the attacker dies)

You are absolutely right! I didn't notice that :o

Another thought occurred to me:

The servants of Haven also have only 1 hit point.

Either one of them is checking, or the police officer is protecting. This is from the rules!

There's a cop, a detective, and a doctor.

The police officer was protecting, and the detective and doctor were checking. This is quite possible.
Two mafia factions on Gura is also an option, but it's strange that no one left any clues.