dangerous, violent
real, serious
habitual, hardened
career, professional
master
petty, street
convicted
known, suspected, wanted
He has been associating with known criminals.

potential
notorious
common
She was treated like a common criminal.

corporate, white-collar
war
He was tried as a war criminal.

catch
I told him to pass the information to the police so they could catch the criminals.

convict, prosecute

Criminal is used with these nouns:
act, action, activity, alien, assault, attorney, background, barrister, behaviour, case, charge, check, code, complaint, conduct, conspiracy, contempt, conviction, court, damage, defendant, enquiry, enterprise, fine, gang, homicide, indictment, intelligence, investigation, involvement, jurisdiction, jury, justice, law, lawyer, liability, libel, litigation, mischief, misconduct, misuse, negligence, offence, past, penalty, procedure, proceedings, prohibition, prosecution, prosecutor, record, responsibility, sanction, sentence, statute, suspect, syndicate, tendency, trial, tribunal, underworld, violation, violence, warrant, waste, wrong