Police have arrested a man they say posted ads online trying to meet young families.

He posted the ads, police say, because he wanted access to the children.

The investigation started about a year ago. That's when officers came across some online postings where a man was looking for a relationship with single parents living in the Newmarket area. Police say that man turned out to be a registered sex offender from Holland Landing in East Gwillimbury.

Frank Cunningham, 33, is facing a number of charges stemming from what police say were his plans to sexually assault children.

York Regional Police and Toronto Police Service have been working together on the case. They say an undercover officer posing as a single mother with two kids got in touch with Cunningham online though some postings he made.

They were postings looking for an 'intimate relationship' with single parents of young kids – babies or toddlers. 

“This person then engaged in several online offences against children, offences that were plotted against children, were committed, and eventually this led to a real-life meeting between Mr. Cunningham and an undercover officer,” says YRP Sgt. Clint Whitney.

That meeting was in Toronto last Tuesday, and Cunningham was arrested. He is now in police custody.

Whitney was part of the investigation that unfolded over the past year. He says the concern now is whether any kids have been assaulted.

“We’re concerned that there are other people out there who have had contact with this person,” he says. “Our investigation leads us to believe that he's had a lot of online activities and there's been a lot of opportunity to contact him. His ads, when he posts them, are rather innocent looking.”

CTV News did a quick search on Craigslist today and found at least one ad, posted last month, police say is his. The title reads: “Any Single Mom For LTR (Long Term Relationship) Dating”

There's a picture attached of a baby's feet.

At the very end of the ad, there's a request that anybody responding include their kids’ ages in the subject line.

A police source confirms to CTV News this is one of the ads posted by the accused.

York Regional Police say that since the arrest they have searched Cunningham's home in Holland Landing and seized computers and alleged child pornography.    

Investigators now believe there may be victims and witnesses who haven’t come forward yet. They are looking for anyone who recognizes him to contact police.

Officers say he has used several email address online, including: dalmarolee@yahoo.ca; toy_f@rocketmail.com; astroboy872@yahoo.ca; Frank.cummingham@yahoo.ca; fcumminhham@gmail.com; body.mods@rocketmail.com; Ecummings@yahoo.ca; Jcummimgs@yahoo.ca; and Rmomo@yahoo.ca.

Cunningham was held in custody and is due in Newmarket court April 17.