Authorities urge vigilance for joggers on Esplanade

“I sometimes see some creepy people around here,’’ said Field, taking a pause during her midday jog along the Charles River. “I would never jog around here at night.’’

Local officials are urging other college students to take similar precautions along one of the city’s most popular jogging sites.

At a press conference outside the Hatch Shell on the Esplanade yesterday morning, officials from Boston, state, transit, and Boston University police urged residents, especially recent arrivals to the city, to be vigilant while walking or jogging in the city at night.

Their warnings came as authorities searched for a suspect believed to be responsible for a string of assaults on the Esplanade in June 2007, July 2007, and July 2009. They believe that person may also be linked to a July 2006 assault at Joe Moakley Park in South Boston.

“We don’t want you to panic, and we don’t want you to live in fear,’’ said Suffolk District Attorney Daniel F. Conley. “We want you to enjoy this beautiful city, but we want you to do it safely and keep an eye out for your friends and fellow citizens.’’

Colonel Marian McGovern, superintendent of the State Police, offered tips on preventing problems while traversing the city at night: Walk with a friend. Carry a cellphone. Avoid poorly lit areas. Take off the headphones. Let someone know when you expect to arrive home.

New students in the area, said McGovern, must remember to practice extra caution in a new city.

“When your years here are done, we want you to return to your families and to your futures with only the best memories of Boston,’’ she said.

Students should also remember that alcohol use impairs judgment at the end of the night, Boston University police Captain Robert Molloy said.

Young people need to watch out for their friends, he said, and ensure that no one attempts to walk home alone late at night.

Yesterday, authorities released a composite image of the suspect believed to be responsible for the Esplanade assaults.

He was described as being clean-shaven, dark-skinned, with a medium build, between 5-foot-8 and 5-foot-10, and in his mid-20s to mid-30s.

“We will never stop in our efforts to identify this man and bring him to justice,’’ McGovern said.

Elizabeth Taistra, 19, a sophomore at Northeastern University, said that news of the attacks has made her careful about where and when she goes jogging.

“Generally, I just run during the day because it’s safer,’’ Taistra said. “Or if I’m running at night, I run with friends.’’

Kirsten Weller, 39, said she used to jog at night, against her better judgment. Now, she said, she is more careful.

She makes sure to do most of her jogging in the daytime. If she goes for a run in the evening, she will leave off her headphones and jog someplace with more nighttime traffic, such as Newbury Street or Commonwealth Avenue.

“It’s not well-lit on parts of the Esplanade, and my husband gets paranoid when I’m out here at night,’’ Weller said.

While Conley said that all residents - men and women, young and old, recent arrivals or longtime residents - should be vigilant when walking along the Esplanade and across the city, others’ concerns about safety when jogging at night mostly fell along gender lines.

Skuli Thorsteinsson, 20, a student at Berklee College of Music, said he was not particularly concerned about attacks that had occurred on the Esplanade, but understood that his female friends might have more cause to be wary of exercising at night.

Eadaoin Snee, 32, of Brighton enjoys running along the Charles River during her lunch break, but said she would never jog along the Esplanade after dark unless she is with a group.

It’s sad, she said, but in most parts of the city, it is simply too unsafe for women to go for a run after sunset.

“I’m often jealous when I see guys running around at night,’’ Snee said.

Martine Powers can be reached at mpowers@globe.com.