Boston police investigators are probing a possible “nexus to gang activity” linking the deaths of five teenage boys in East Boston in the past 15 months — the latest a young man found fatally stabbed near Memorial Park late Christmas Eve, police Commissioner William B. Evans told the Herald.

“We’ve been looking at how they are connected to each other,” Evans said. “This is the stuff that keeps me awake at night. It’s disturbing when you get a call about a young kid murdered like that in the city.”

Evans said as of last night, authorities had not identified the victim, who was discovered about 10:45 p.m. Saturday near the East Boston park and Logan International Airport. Police said the victim appeared to be in his late teens and had suffered “apparent stab wounds.”

The body was the second found in East Boston this month. On Dec. 9, the partially decomposed body of a 16-year-old boy from the neighborhood was found at the Belle Isle Marsh Reservation. State police are investigating that death, and his name and cause of death have not been made public.

Evans said his homicide detectives are working with state police to probe not only if there are any ties between the discovery of Saturday’s body and the body at the Belle Isle marsh, but also three slayings linked to MS-13 going back to last year.

All three of those victims were Latino teenage boys:

• Wilson Martinez, 15, was found fatally stabbed on Constitution Beach on Sept. 7, 2015. Martinez had lived in Boston only a few years since immigrating from his native El Salvador.

• Irvin de Paz Castro, 15, was found fatally stabbed on Sept. 20, 2015, on Trenton Street in East Boston. He was also a native of El Salvador.

• Cristofer Perez de La Cruz, 16, was shot, slashed and had his hand hacked Jan. 10 by MS-13 members for allegedly being in a rival gang, authorities have said. He was a native of Guatemala.

“Clearly, there is a lot of youth violence. We’re not sure if it’s MS-13 or 18th Street, like in the past,” Evans said. “But I’ve got to believe that’s what’s going on here.”

Evans noted U.S. Attorney Carmen M. Ortiz indicted more than five dozen MS-13 gang members in January, alleging members of the vicious gang had been ordered to kill rival 18th Street members, and the bloody warfare was playing out in East Boston and Chelsea streets. The indictments specifically alleged the murders of Martinez, de Paz Castro and Perez de La Cruz had been carried out by gang members.

“The U.S. Attorney, when she handed out the indictments, (gang violence) was their focus,” Evans said. “It’s disturbing when you have so many young kids found in one part of the city. Clearly, we’re looking at the nexus to gang activity.”

Ortiz’s racketeering indictments alleged the ruthless gang — with ties to El Salvador and operates with the motto “Kill. Rape. Control” — was responsible for five murders, including the three teenagers in East Boston.

At Memorial Park yesterday afternoon, hours after the body was found, life went on as usual. Children played on swing sets, kicked soccer balls and rode scooters, while some adults ran around a track or walked dogs.

But the string of deaths was not far away from the minds of some residents.

“I’m scared. I’m sad. I feel pity,” Edgar Reyes, who has lived in Eastie for a dozen years, said in Spanish. “It’s unconscionable this is happening to our youth. They are our youngest. They are children. Everyone deserves to be safe — especially children.”