Elizabeth Ross mourns the loss of her 18-year-old son Markel Ross who was shot and killed, on September 11, 2012 in Capitol Heights, Maryland. (Astrid Riecken/FOR THE WASHINGTON POST)

The teens were strangers to each other — living miles apart and attending different high schools in Prince George’s County. Although they shared an interest in modeling, their paths never crossed, family members said.

During the first month of classes, both were fatally shot. Homicide detectives do not think the slayings of 17-year-old Amber Stanley and 18-year-old Marckel Ross are connected, police said Wednesday. But they also have no clear explanation as to why Stanley, a Charles H. Flowers High School student who aspired to attend Harvard, was killed in her bedroom in Kettering last month, and Ross, a track athlete who loved dancing, was gunned down as he walked to school Tuesday.

Assistant Prince George’s Police Chief Kevin Davis said investigators have leads but no suspects in both cases. And he said the department is dedicating significant manpower and other resources to solving the homicides.

“We all can relate to it, because our kids walk to school, they go to class, they put a book bag on and leave,” Davis said. “It gets intense dedication and commitment from the police department.”

Even before Ross was killed on his way to Central High School, police had assigned an entire homicide squad to investigate Stanley’s slaying — a step reserved for only the most serious cases. Davis said that police would take the same step in Ross’s case and that commanders would seek daily updates on both investigations.

Police also assigned two extra school resource officers to Central High School, where Ross was a junior, in hopes that students might approach them with tips and feel comforted by their presence, Davis said. He said other officers have fanned out across the Capitol Heights neighborhood where Ross was killed, handing out fliers and posting signs seeking information. They took similar steps in investigating Stanley’s slaying, Davis said.

The two killings come in a year when crime is down significantly in Prince George’s. As of Wednesday, the county had recorded 48 homicides in 2012, compared with 74 during the same time period the year before, authorities said. Overall, crime is down 7.4 percent, violent crime has fallen 5.1 percent and property crime has dropped 7.7 percent this year compared with the same time period last year, authorities said.

“We’re working very hard on it,” Prince George’s Police Chief Mark Magaw said after a Metropolitan Washington Council of Governments meeting Wednesday. “It’s almost gotten to the point of how can that happen here?”

Prince George’s School Superintendent Alvin Crawley said the school system deployed a team of grief counselors to Central High on Tuesday. Some of the same counselors assisted students and faculty at Flowers High only three weeks earlier.

“We see both of these as tragic incidents that impact the entire community,” Crawley said. “We are looking for community organizations to come together to take a look at what is happening with our young people to ensure their safety.”

Stanley, who was just beginning her senior year, was shot to death by an armed intruder who burst into her family’s home on Chartsey Street about 10:30 p.m. Aug. 22. Although investigators do not think the slaying was random, they have no suspects or motive, authorities have said.

Ross was walking to Central on Tuesday morning when he was killed in the 6100 block of Old Central Avenue.

Amber Stanley. (Courtesy of Prince George's Public Schools)

Police haven’t focused on “one particular motive” in his slaying, Davis said. He said there was no immediate sign that the teenager had been robbed, although detectives have not ruled out that possibility because he might have been carrying something they did not know about.

Relatives of both teens said Wednesday that the two did not know each other — despite their shared interest in modeling and fashion. Stanley, family members said, worked semiprofessionally as a model, and Ross’s experience seemed limited to a program at his school. Neither teen spent time with students from the other’s school.

Still, family members said they were thankful for the attention that Ross’s and Stanley’s cases were receiving. Irma Gaither, Stanley’s mother, said she was encouraged to hear that detectives had been specially assigned to investigate her daughter’s slaying and was hopeful that they could close the case.

“It would be nice if they could have solved it in 24 hours like the TV shows, but it don’t work that way, I guess,” Gaither said. “They really, really trying to do this. I’m positive they will find someone, or someone will tip them off, because they got so many people working on it, and it’s a high-profile case.”

Allison Klein contributed to this report.