It was before 9 on a Saturday night this month when a CSX engineer notified police that he had discovered the body of an 18-year-old woman along railroad tracks in Southeast Baltimore.

When Baltimore Police officers arrived and began assessing the scene, they saw the body of Michelle Tenezaca in the brush. She had been stabbed multiple times. But soon after, they found a second victim, yards away and still clinging to life.

It was Tenezaca’s 17-year-old sister. Both had been stabbed dozens of times, and the case soon linked detectives up with police in Baltimore County, who said the surviving girl’s boyfriend had been found stabbed near the waterfront in Turner Station. He survived.

Now authorities in the city and county are investigating the involvement of MS-13, a transnational gang that till now in Maryland has largely been linked to violence in the D.C. suburbs.

Although suspects have been charged in the nonfatal stabbings, no one has been charged in Tenezaca’s death.

Baltimore County police have charged three men in the attack on the boyfriend, who was 17, and said his attackers had been trying to recruit him into the MS-13 gang since December.

On June 6, the boy and his girlfriend were approached by members of the gang and forced onto a bus on Eastern Avenue in Southeast Baltimore, police wrote in court records; the two complied out of fear.

At Turner Station, the male victim was taken into a wooded area in the 800 block of Avondale Road near the water and was beaten and stabbed repeatedly. He told police his girlfriend was taken to a separate location by other people.

The charging documents say the girl was later found with life-threatening stabbing injuries “off Eastern [Avenue].”

City police had previously confirmed that a 17-year-old girl was found injured next to railroad tracks in the 4500 block of E. Lombard St. that night.

In charging documents for her case filed in the city, police indicate the train engineer first saw Tenezaca’s body, and that her sister was found a short time later when police arrived.

The circumstances of Tenezaca’s killing are unclear. Police wrote in court records that her sister was seen earlier in the night walking with two men, but they do not describe Tenezaca’s movements.

County officers canvassing the Turner Station area for suspects after speaking with the male victim said they found 19-year-old Jonathan Pesquera, who said he was in the area looking for his girlfriend. Two others, Edys Valenzuela-Rodriguez and Wulater Hernandez Orellana, were found on a different street; court records also list them as 19 years old. All were identified as having been involved in the attack, police said.

Police said in charging documents that the men “provided conflicting information as far as what they were doing in Turners [sic] Station and who they were with in Turners Station.”

They are facing charges of second-degree attempted murder, assault and kidnapping, and are being held without bail. They did not have attorneys listed in court records.

City police also charged a man in connection with the nonfatal stabbing of the sister. Carlos Eduardo Diaz, 17, was apprehended June 11 in the 800 block of E. Baltimore St. and charged with attempted first-degree murder and related charges. They say he is shown on tape walking with the younger sister.

MS-13 is a gang with roots in El Salvador and which law enforcement experts say counts thousands of members across the country. In Maryland, federal prosecutors have said it has operated primarily in Anne Arundel, Frederick, Montgomery and Prince George’s counties.

There have been no known MS-13 killings in Baltimore City.

Police said last fall that a killing in Towson was linked to the gang. Detectives alleged that members of MS-13 stalked 21-year-old Daniel Alejandro Alvarado Cuellar home from a laundromat in July and stabbed him to death — one killer allegedly armed with a machete-style knife — outside his apartment in Towson. Investigators attributed the killing to a war between two Latino street gangs, 18th Street and MS-13.

“The victim had been seen making a hand gesture that was believed to be indicative of an affiliation with the 18th Street,” detectives wrote in charging documents.

That case is pending in Baltimore County Circuit Court.

County and city police also said they are consulting with each other about whether there is any connection to a killing of another teen girl whose body was found near the Loch Raven Reservoir on May 31.

Sixteen-year-old Gabriella Alejandra Gonzalez Ardon, who had been reported missing from Long Island last year, was found May 29 near the reservoir.

“Nothing has been verified at this point,” Baltimore County Police spokeswoman Jennifer Peach said of any possible connections. “It is still an ongoing investigation so we can’t release any more information at this time.”

Said Det. Donny Moses, a city police spokesman: “We are working with other agencies to get to the bottom of what happened to both girls.”

Ardon’s family had reported her missing from Glen Cove, New York, in late March 2019 when she was 15 and last seen on a beach, Nassau County Police on Long Island said last year.

Her family identified Ardon by photos of her tattoos circulated by police on social media.

Nassau police believed Ardon was traveling to Baltimore, they said in a 2019 news release.

Ardon’s body was found by a pedestrian shortly before 10 a.m. May 29 along Merryman’s Trail in the woods off Pot Spring Road near Colonnade Road in Cockeysville. No other information has been released about the case.

Last fall, four people pleaded guilty in U.S. District Court to participating in two grisly murders in Anne Arundel County as part of MS-13 — the killing of a 21-year-old Annapolis woman who was found buried in a secret grave in a Crownsville park in September 2017.

One of the defendants also admitted to aiding in the murder of a 17-year-old who was found buried the following month in Annapolis.

Those killings were also said to be tied to a rivalry with the 18th Street Gang, according to the plea agreements.

Baltimore Sun Media reporter Taylor DeVille contributed to this article.