Boston (WBZ Newsroom)  -- Boston police hope a new picture will find the man responsible for several assaults along the Esplanade last summer.

The new image was developed from the victim of a July 29, 2007 attack (the original sketch is at right). Forensic evidence linked her assailant to two other sexual assaults -- one on June 16, 2007 near the Esplanade and the other on July 29, 2006 at the Moakley Park in South Boston.

The suspect is described as a clean-shaven black man in his mid 20s to mid 30s, standing 5 feet 8 inches tall to 5 feet 10 inches tall.

Police don't know his identity and they want to talk to five people in the area at the time of the attacks and who may have seen the suspect.

Specifically investigators would like to speak with a lone man who was near one of the footbridges at about 11:15 on the night of June 16, 2007. That individual saw the victim and the assailant.

Police also want to talk with a pair of bicyclists wearing helmets and cycling gear who were walking their bikes near the footbridges between 4:30 and 5:00 a.m. on July 29, 2007. They saw the assailant and the second victim, prompting the assailant to put his arm around the woman as if they were a couple.

In addition, a man and woman, both well-dressed and in their late 20s, who were near Joes American Bar and Grill at the intersection of Dartmouth and Newbury streets between 5 a.m. and 5:30 a.m. on July 29, 2007 are also sought.

In the July 29, 2007, incident, a 20-year-old woman was abducted at knifepoint on Beacon Street and forced to walk to the Esplanade, where she was sexually assaulted and robbed at about 3:30 a.m.

In the June 16, 2007, incident, a different 20-year-old woman was jogging at the Charles River Esplanade on a footpath near the Massachusetts Avenue bridge shortly after 11:00 p.m. when she was sexually assaulted.

In the July 29, 2006, incident, a 30-year-old woman was in the area of Joe Moakley Park when she was sexually assaulted at about 3 a.m.

Anyone with information is asked to contact State Police at 617-727-6780. Anonymous tips can be placed at 1-800-494-TIPS.