John, youre right. Not arrest him but not allow him to depart the building until questioned. Is that detain for questioning I guess.
From what I've read, the courts have long held that in "exigent" or emergency situations that people's Fourth Amendment rights against illegal searches and seizures can be suspended.
This is clearly for me one of those instances. Was Baker supposed to get a search warrant? Stop and ask Oswald questions?
Although who knows what the Oswald defenders will say in response. It's always a crapshoot.