Toronto police have made another arrest in an ongoing abduction investigation on the University of Toronto campus, but say one suspect remains outstanding.

In November, a 21-year-old man was walking downtown when he was approached by four individuals.

They allege one pulled out a stun gun while another choked and robbed him. They also allege the men forced the victim to withdraw money from a bank machine and later took him to a motel where they held him until he raised his credit limit.

The victim was only released after they emptied his bank account, police say.

Police had earlier arrested two men and two women in the ongoing probe.

Now, a 19-year-old man has also been charged with kidnapping for ransom, forcible confinement, robbery and assault along with credit card-related offences.

Police say they believe there may be other victims and are encouraging anyone with information to come forward.