A 25-year-old Ottawa man was charged with one count of sexual assault in an incident police say is connected to the series of assaults in the last month where women's pants were pulled down.

Gavin Sean Griffiths, 25, was arrested on Wednesday evening while he was riding a public transit bus in the city's west end.

He was charged with one count of sexual assault, one count of mischief and one breach of probation in connection with an incident that occurred on April 16, near Loretta Street and Young Street.

The arrest of Gavin Sean Griffiths was shocking to both friends and family. (Facebook)

Police say more charges are expected to be laid.

The arrest comes after a series of incidents that occurred between April 14 and May 7 in which women reported a man approaching them from behind and pulling their pants down.

Police had released a composite sketch of the suspect and had asked the public for help in apprehending him.

OC Transpo video helps officers

Excerpts of video from OC Transpo surveillance were given to officers across the entire police force. Griffiths was identified by officers on surveillance who then redirected to trail him to his home. He was then put on 24-hour surveillance until the arrest was made.

"This was a concern to everyone in the Ottawa Police Service, all our officers were aware of who we were looking for," said Inspector John Maxwell with the criminal investigations unit.

Griffiths had a prior record, but no prior sexual assaults, said Maxwell.

Griffiths' arrest was a shock to his friend Shawn Lafleur, who said Griffiths was "a great guy" despite past troubles with the law.

"He's been blamed for many things before, ever since he's been in Ottawa he's been getting arrested for nothing, absolutely nothing," said Lafleur. "And now this. It makes me sick."