Authorities investigating the seven-year disappearance of missing British girl Madeleine McCann are honing in on a man who sexually assaulted young girls near the Portuguese resort where Madeleine was last seen.

Investigators are trying to identify the man, whom they believe carried out a series of 12 crimes inside villas mainly occupied by British families vacationing in the Western Algarve region of Portugal, the UK’s Metropolitan Police said in an appeal Wednesday for more information in the Madeleine McCann case. The crimes were committed between 2004 and 2010, with four of the cases involving sexual assaults of young, white girls between 7 and 10 years old. Two of the incidents occurred in Praia de Luz, the same resort town where the McCanns were staying.

Madeleine was 3 years old when she went missing May 3, 2007, from a resort in Praia de Luz resort as her parents dined with friends and she was left in the villa where her family was vacationing. The missing British girl’s case is arguably the most high-profile missing persons’ case in the world. Metropolitan Police has put out a £20,000 reward ($33,250) for information leading to the identification, arrest and prosecution of anyone responsible for Madeleine’s abduction.

In the villa break-ins, there were largely no signs of forced entry and nothing was taken from the dwellings, according to Metropolitan Police. The sexual assault suspect usually appeared in the early morning hours. He may have either be in the villas or looking around the villas before committing the crimes or having his plans foiled by parents who were disturbed by their child waking up.

Witnesses have described the man as being tanned with short, dark unkempt hair. He was bare chested during some of the crimes and some witnesses described him as having a pot belly. Three victims said he had a “noticeable odor.” They said he spoke English with a foreign accent and described his voice as slow or possibly slurred.

Metropolitan Police Detective Chief Inspector Andy Redwood said investigators are trying to learn more about the man, in part to determine whether he has any connection to Madeleine’s disappearance.

 “We need to establish the identity of this man,” Redwood said in a statement. “These offenses are very serious and no one has been charged in connection with them. We also need to eliminate this man from our enquiries and ascertain whether these offences are linked to Madeleine’s disappearance.”

Redwood also asked anyone who has been the victim of a similar crime to report the incident to Portuguese authorities. He also noted that an appeal for information distributed in October was a success that led to similar crimes being reported.

“While some of these offences have been in the public domain before, following our appeal in October three more were reported to us as a direct result of that appeal. One of those reports we believe is the first in the potential series,” he said. “Our appeal last year was very successful and we had over 5,000 calls which generated new information for us and which we continue to investigate.”