Two state troopers on foot patrol interrupted a sexual assault early Sunday morning in the Boston Esplanade.
The incident unfolded at about 1 a.m., near Longfellow Bridge, where two troopers on foot allegedly saw the attack and took the suspect into custody for indecent assault and battery.
Joseph Barthel, 49, is expected to be arraigned Monday in Boston Municipal Court.
Based on the evidence developed thus far, this incident does not appear to be linked to a series of unsolved sexual assaults on the Esplanade, which involve a suspect who does not match this defendant's description.
Investigators said they will compare the facts and circumstances to unsolved attacks to determine if there are any links.