Probably not most legal but someone is at risk - UK

Long story short, i lend money. Guy (real name) Harry Ennis, stole Guy (real name) Derek Bayleighs passport and is using it to lend money online, along with deepfakes and ai. Harry tried to lend 20 quids off me and i caught on pretty quick. Now Harry has probably used Derek's passport and will use it again, how do i help Derek. And no 101 isnt an option because lending money is not legal. Im 17