A week after the bodies of two transgender women were found in a badly burned car in Puerto Rico, the police said Thursday that they had arrested two men in connection with the killings and had turned them over to the F.B.I.
The men, Juan Carlos Pagán Bonilla, 21, and Sean Díaz de León, 19, were taken into custody on Wednesday but have not been charged, according to Capt. Teddy Morales, the chief of criminal investigations for the police in Humacao, on Puerto Rico’s eastern coast, where the women’s remains were found on April 22.
He said the F.B.I. had taken over the case and was investigating Mr. Bonilla and Mr. de León for possible civil rights violations.
“We are classifying it as a hate crime because they were socializing with the victims, and once they found out they were transgender women, they decided to kill them,” Captain Morales said on Thursday.
The police said they were waiting for autopsy results to determine how the women had been killed. Activists have identified the women as Layla Peláez, 21, and Serena Angelique Velázquez, 32, two friends who lived in New York City. Their remains were found after a person called 911 to report a burned car under a bridge on a desolate road in Humacao, just before 5 a.m. on April 22, Captain Morales said.
Mr. Bonilla and Mr. de León had been socializing with Ms. Velázquez and Ms. Peláez on the night before they were killed and were recorded on one of the women’s social media accounts, Captain Morales said.
He said the police had also tied Mr. Bonilla and Mr. de León to the killings through security camera footage and “scientific evidence,” which he declined to detail. Mr. Bonilla confessed to participating in the killings, and Mr. de León turned himself in, he said.
Limary Cruz-Rubio, a spokeswoman for the F.B.I.’s San Juan field office, declined to discuss the arrests but said the bureau routinely collaborates with local, state and federal agencies.
“The Bureau is and will always be interested in criminal conduct which may fall within federal jurisdiction,” she said. “However, our policy is we do not to confirm or deny the existence of investigations, to protect the integrity of any possible investigative effort.”
Mr. Bonilla and Mr. de León could not immediately be reached for comment on Thursday night, and it was not immediately clear if they had lawyers.
If the men are charged, it could represent a turning point in the handling of crimes against L.G.B.T.Q. people in Puerto Rico, which has a disturbing history of violence against gay and transgender people, activists said.
Ms. Velázquez and Ms. Peláez were the third and fourth transgender people killed in Puerto Rico in the last two months, activists said. They were also believed to be the seventh and eighth transgender or gender-nonconforming people to have been killed in the United States this year, according to the Human Rights Campaign.
In the past 15 months, 10 L.G.B.T.Q. people have been killed in Puerto Rico, according to Pedro Julio Serrano, a gay rights activist. All but three of the deaths remain unsolved, he said.
“These arrests are a step in the right direction, but these murders have to be prosecuted as hate crimes,” Mr. Serrano said. “We urge the government to finish the investigations in the other seven murders of L.G.B.T.Q. people on the island and serve justice for all of them.”
Ms. Velázquez lived in Queens and Ms. Peláez in the Bronx. Both had recently traveled to Puerto Rico, and they were planning to fly back to New York later this month, according to family members and activists.
Luz Melendez, 29, Ms. Peláez’s cousin, said Mr. Bonilla and Mr. de León were arrested after a local radio station posted images of them on Facebook and people began to call the station to identify them.
“We are super appreciative of the work that the officials and the community put in to find who did this,” she said on Thursday.
She said the images came from two videos that Ms. Peláez had posted on her Snapchat and Facebook accounts, which showed her and Ms. Velázquez socializing with Mr. Bonilla and Mr. de León.
“I saw the videos, and it seemed like they were spending time together as friends,” she said. “It seemed normal. There was music playing in the background. Everyone seemed fine.”
She said the police had told her family only that the men were in federal custody.
The killings came a month after Yampi Méndez Arocho, a 19-year-old transgender man, was killed in Moca, P.R., according to the Human Rights Campaign.
Ms. Negrón’s final moments — framed in the headlights of a car amid a cackle of laughter — were posted on social media, a fact that activists said underscored the impunity homophobic attackers feel when committing such crimes.