Detectives tasked with solving the killing of Zoe Spears started with only a sliver of evidence: grainy black-and-white images of a Dodge Caravan.

Determined to learn who killed the transgender woman found on a sidewalk June 13 in a D.C. suburb, detectives began piecing together the story of the van.

They asked motor vehicle divisions in the District, Maryland and Virginia for all of their records of Dodge Caravans, netting more than 50,000 results. They called Dodge dealerships and learned the van was a distinct model with a unique silver color. The search narrowed to 3,000.

Detectives then asked police agencies from across the region to return any hits from license plate readers related to the specific model and color of the 2018 van. As they sifted through 30,000 hits, police said, detectives struck gold — or, rather, Dodge “billet silver.”

Investigators, according to charging documents, found only one license plate hit for a matching van in the area of the shooting: a rental out of Baltimore scanned only a half a mile away about two hours before Spears’s slaying.

Five weeks after Spears was fatally shot and 50,000 vans later, Prince George’s County police announced Thursday that they had arrested the man behind the wheel of the Dodge caught on camera.

Detectives charged Gerardo Thomas, 33, with first-degree murder after he admitted to being at the scene and armed in the van the night of Spears’s killing, said Brian Reilly, head of the criminal investigations division for the county police.

Officials said they still are investigating the motive but do not believe Spears, 23, was targeted because of her gender. Police also said they do not believe the killing was connected to the fatal shooting in the same area three months earlier of Ashanti Carmon, who was friends with Spears.

Carmon, 27, was shot several times, and her body was found about 6:20 a.m. March 30 in the 5000 block of Jost Street, less than half a mile away from where Spears was found.

“He did not mention anything about her being a transgender female,” Reilly said of Thomas, adding that Thomas told police he was in the area at the time but did not tell them he had killed Spears. Asked whether Thomas discussed a reason for his alleged crime, Reilly said, “He gave us no reason.”

Online court records did not list an attorney for Thomas in Spears’s killing, and an attorney’s office representing Thomas in an unrelated case said it did not have information on this week’s arrest.

Police recovered a shotgun Wednesday while executing a search warrant on Thomas’s home in Baltimore and are working to determine if investigators can link the weapon to the shotgun that killed Spears, Reilly said.

Spears, of Northwest Washington, told friends she feared returning to her home along Eastern Avenue at the District-Maryland line because she had witnessed her friend Carmon’s killing in that area. Reilly said police spoke with Spears after Carmon’s death but do not believe Spears was killed because she was a witness. Carmon’s case remains unsolved.

The killings of the two women less than three months apart put the transgender community on edge, with advocates demanding more services to protect the population.

Prince George’s and Fairmount Heights police have stepped up patrols in the area where Carmon and Spears were killed. And advocates have urged transgender people to stay away from the stretch along Eastern Avenue known to be a gathering place for sex workers.

The announcement of Thomas’s arrest was made days after Spears’s funeral.

Spears moved to the District at 19 and signed for her first apartment along Eastern Avenue in Northeast Washington in 2017, according to her memorial program.

With her new independence, Spears worked in retail and hoped to be a lawyer, the program said.

“To know Zoe was to know her loving and caring spirit,” her funeral program said. “There are many who would say that Zoe was one who [loved] life and wanted to make it.”

But friends said Spears also had a difficult life.

Surveillance video from a building across the street captured Spears’s killing, but she is seen on the side of the van farthest from the camera.

Spears is seen approaching the Dodge Caravan from the passenger side and speaking with at least one person through the passenger-side window, according to charging documents.

“Seconds later, what appears to be muzzle flash can be seen and then the silver Dodge Caravan drives off,” charging documents said. Spears collapses, according to the documents.

Though the surveillance video was black and white, police were able to determine the van was silver after reaching a local Dodge dealership. One of the salesmen, a former police officer, noticed that the specific body and features of the car pictured are only associated with that particular color, Reilly said.

After detectives found the van they believed was in the video, they contacted the rental company that surfaced in the license plan scans, which had information showing the car was being rented to Thomas after he had been in a car accident, Reilly said.

The arrest, Reilly said, was due to the “tireless, tedious, hard work” of homicide detectives.

“We handle every single murder the same way,” Reilly said. “We fight along with the family members to bring justice.”