y'all both wrong
to arrest someone, you need to charge them with a crime... to charge them with a crime, you need an arrest warrant unless you're a cop who personally witnessed this thing going down
which means you need to go to a judge, and get a warrant to arrest this man
so barring angela going in there to say "yes i saw james with him" or "james told me straight up he did it" or "yes i know james deals drugs and greg was after him"....... ain't no judge in the world going to sign that paperwork
all she has is, james said he saw him that night... james prints were at the scene... that's it... no gun (cause he didn't do it), didn't even check to see he wasn't somewhere else at the time (he was), didn't get any forensics or nothing back yet, etc etc
again.. you can have him brought in for questioning.. you can hold him for 24 hours... but you can't just arrest the man, charge him with murder, and put him in jail over fingerprints at a house you don't even know if he was invited to or not
but ummm...... why would ghost break in an fbi agents house with no damn gloves on