Beein in jail 1 out of 5 years for violent retribution against tradesmen who abused a villager.

Gabriel was imprisoned in Tearmark prison, following a disagreement with a local guard, on how much it would be to let Gabriel and the caravan he was escorting enter the city. Refusing to pay the corrupt guard, Gabriel ended in Tearmark.
 

The escape from Tearmark

Together the party of Gabriel , Roboute Guilliman  and Aramil , Gabriel aided Doctor Terp Quint 's escape from Tearmark prison.
Here Gabriel would aggressively cut down multiple guardsmen, leaving only Guardsman Henry alive. Robute suffered a spear to the abdomen, nearly passing on to the afterlife, if not for a Healing Touch by Aramil.

Involvement in the murder of Terp and raid on the abandoned mines

Doctor Quint revealed conspirations that Matteus Candentes  was involved in a plot against the king and had been involved in the alleged murder of King Carial Parlent, possibly working with The Masked Council .
 
While Aramil successfully detected the arrival of a Masked Assasin, the party failed to stop this man; who, with help from and unfortunate Thunder Wave by Eramil knocking Terp unconscious, killed Terp Quint. A following disagreement between Roboute and the remaining party on wether to slay the assassin or let him be on his way, resulted in the assassin escaping; whilst leaving a letter to the adventures from the Masked Council offering an alliance.
 
The party however rejected this alliance, instead siding with the arriving soldiers of The Magistrate , led by Bartolleus Flech , and raided the abandoned mine to which the assassin had fled. In there the party murdered multiple thugs of the order as well as an acolyte who turned out to be the host of a monstrous Gibbering Mouther, barely slain.