The victims: Judith and Stephanie Emile.A fugitive sought for the 2011 double-murder of two Haitian-American sisters in Dorchester has been placed on the US Marshals “15 Most Wanted” list. After four and a half years of searching for the man, the Marshals Service is offering a $25,000 reward for information leading to his arrest.

Three years after Haitian-born Jean Weevins Janvier became a naturalized US citizen, he allegedly killed 23-year-old Judith Emile and 21-year-old Stephanie Emile, with whom he had previously been romantically involved, according to Suffolk County District Attorney Daniel Conley’s office.

JanvierJanvier, 34, is wanted by Boston police and the district attorney’s office on two counts of first-degree murder, two counts of armed assault in a dwelling, and carrying a firearm without a license.

Police responded to the Emile sisters’ Harlem Street apartment at about 9:15 a.m. on Nov. 15, 2011, a mild fall morning. The young women inside had suffered fatal gunshot wounds after being shot “execution style” and left in the yellow-brick building, according to officials. Police found a two-year-old toddler, a niece of the sisters, alive but alone with their bodies.

The Homicide Unit identified Janvier as “the person responsible for the homicides” in early February 2012. By then, he was believed to have fled the state and possibly the country, leading authorities to appeal for the community’s help in locating the former Dorchester resident. He is described as a 6-foot-1-inch black male weighing approximately 150 pounds, with black hair and brown eyes.

Police cited ”numerous interviews, along with the recovery of forensic evidence, which ultimately led to the issuance of an arrest warrant for Janvier.” Today, his whereabouts are unknown. Given the nature of his accused crime, Janvier is considered armed and dangerous.

“It is difficult to imagine what kind of malicious individual could perform the unspeakable crime Jean Janvier allegedly committed that took the lives of two young sisters,” said US Marshals Service Deputy Director David Harlow in a statement. “The US Marshals will dedicate all our available resources along with the help of our federal, state, and local law enforcement partners to bring Janvier to justice and answer for these heinous crimes.”

Janvier arrived in the United States in 1997, according to the Marshals, becoming a naturalized citizen in 2008. He is believed to have relatives in Haiti and Montreal, although the marshals emphasized this week that they are not ruling out the possibility he is still in the United States.

“It’s fair to say there’s no way this guy is still in Massachusetts,” said US Marshal Neil Sullivan, who works on the fugitive task force in Boston.

Few cases ever make it to the Top 15 Most Wanted list, the marshals said, with hundreds of files submitted for consideration each year and only three or four spots opening annually. “When it gets to this level, it is such a priority,” Sullivan said.

“It’s a horrendous crime,” he said. “Two young Haitian women at the beginning of their careers, and they were violently taken away from their families.” They have had no closure on the loss of their dedicated and hardworking sisters, Sullivan said.

Sullivan estimates that most fugitives are apprehended by the Marshals Service within a year. The Top 15 list comes with additional resources, funding, and visibility, he said.

The last Massachusetts fugitive to be added to the Top 15 was Peter Castillo, charged with shooting and killing Army veteran Stephen Perez in Boston’s Theater district in 2012. Upgraded to the Top 15 in October 2014, Castillo was arrested in the Dominican Republic the following January.

Although the marshals have been on the Janvier case since Boston police requested their assistance in 2012, there have been few leads. As the investigation remains active, specifics on the efforts to apprehend Janvier are not being released.

“I commend the work of the US Marshals Service and the Boston Police Department for their ongoing efforts to seek justice for the Emile family and bring them some level of comfort,” said Boston Police Commissioner William Evans in a statement.

Boston police and the US Marshals ask that anyone with a tip contact the Marshals office in Boston at 617-748-2600.