Timothy Day (Suffolk County District Attorney’s Office)

Timothy Day was arraigned Monday in Suffolk Superior Court in Boston on a single count of indecent assault and battery for a 2004 incident on that city’s subway.

Boston area and Metro Transit police say he is also a suspect in an incident on May 16, 2002 on a Metro train.

In that case, a female reported to Metro Transit Police that she was approached by a man around 8:25 a.m. while boarding a train at the Pentagon station. According to the police report, she said the “subject ground his hips into her buttocks area.”

The man was identified only as John Doe and described as being between 30 and 40 years old, weighing 190 pounds and was reported as last seen wearing a blue coat.

Day’s case was reported Monday in the BethesdaPatch.

In the Boston case, which happened on June 22, 2004, a 23-year-old woman reported that a man — who police later identified as Day — was “pressing against her from behind” on a crowded B Line subway train after a Red Sox game, according to Boston police and prosecutors.

The woman later noticed that the man had ejaculated on her shoulder bag and pants, according to Lewis Best, deputy chief of Massachusetts Bay Transportation Authority Transit Police in a phone interview. The evidence was seized and taken to a Boston police crime lab and in November 2004 it was linked to the similar case on Metro’s train.

Day’s DNA profile had “been entered into” a database “following a federal conviction,” and it was matched to the two subway assault cases, according to Boston officials.

Day was represented by lawyer Peter Elikann, Boston officials said, in the Suffolk County case. Elikann did not return a phone message left at his office.

Metro chief spokesman Dan Stessel said in an e-mail “we are discussing the case with the Commonwealth’s Attorney at this time.”

Metro has come under harsh criticism recently that it was not doing enough to deal with reports of sexual harassment and similar complaints on its bus and rail systems. Since then the agency has been working to encourage riders to report such incidents to authorities through an e-mail address and Web site.

Its program is modeled after Boston’s, where authorities said they started an aggressive campaign three years ago for riders to report such incidents.

This week, Boston’s subway system also launched a smartphone app called “See Say” where riders can send in pictures, text and incident location details on suspicious activity.”

Follow me on Twitter @postmetrogirl.