"We'll take it into consideration... You may join this investigation if you like, Hunter." said the Legate to Johann.
"But from what I've heard, the halfling was assaulted by some of these mercenaries, not the soldiers of our fort. A man's body was found speared on the fountain in the square, with signs of magical damage. He is the only one who has displayed magical use so flagrantly from what I hear, so it's a simple thought to conclude he's suspect. We're not so callous as to not entertain the thought he's innocent, but we need to take him into custody for now. So he isn't killed, or if he is the perpetrator he doesn't run." He snapped his fingers, and the fort soldiers began shackling Finn. He then turned to Greta, regarding her.
"Absolutely. He will be notified that one of his bodyguards is a suspect in a murder."
He regarded the party of vouchers as a whole, looking each of them in the eye as he spoke.
"Rest assured, we don't have the lack of control that untrained mercenaries do. He won't be beaten any further. In fact, his wounds will be seen to first." He turned his voice to the crowd.
"As for this assault... This is a land of laws, people. We will, too, be arresting the instigators of this crime as well. Step forward, so everybody else can leave sooner."
Despite the noble intentions that blooded mercenaries are known for, the conscious brawlers seemed reticent to come forward, trying to blend with the crowd.
OOC:
You can try to stop them from shackling him if you like physically, but I won't include persuasion here. It lines up too well for an initial accusation xD. Dang you all, I had this planned from the start, but he just had to run around mage-handing everything and be suspicious.