PROVIDENCE — David J. Cartagena, a senior street worker for the Institute for the Study & Practice of Nonviolence, had put his troubled past behind him. The former member of the Almighty Latin King Nation youth gang had spent plenty of time in the Adult Correctional Institutions and, in his teens, in the state Training School.

His life changed in 2005 when he joined the staff of the nonprofit agency and became one of its most effective leaders in combating gang violence and youth crime.

Shortly after 2 a.m. Sunday, Cartagena, 38, was killed in a chain-reaction collision involving his vehicle and three others on Route 95 near the Providence Place mall. Two of the other drivers face alcohol-related charges.

State police Lt. Frank Sullivan gave this account, which he stressed was preliminary pending a review by a reconstruction team:

Cartagena was northbound in his Lexus sport-utility vehicle when he struck a Jeep Cherokee stopped in the breakdown lane and protruding into the travel lane. A Jeep Wrangler driven by Steven Croteau then slammed into Cartagena’s vehicle. Cartagena got out of his SUV and was hit by a Honda Civic driven by Jeffrey Lopes that had caromed off the center median barrier.

Lopes, 21, of 7 Pleasant St., Cumberland, was charged with driving while intoxicated, Sullivan said, and Croteau, 22, 752 Iron Mine Hill Rd., North Smithfield, was charged with refusing to take a chemical breath test. Both were released after appearances before a bail commissioner at the Lincoln barracks.

Neither Lopes nor Croteau was hurt, according to Sullivan. But a North Smithfield resident who was riding in Croteau’s car was admitted to Rhode Island Hospital with injuries not considered life threatening, he said.

Two others, the driver and a passenger in the disabled Cherokee, also were admitted to Rhode Island Hospital, according to Sullivan, who identified them only as Providence residents. Their injuries were not serious, he said.

On the city’s South Side, stunned street workers, support staff and friends gathered at the Institute for Nonviolence to share their grief. Teny Gross, the institute’s executive director, was particularly close to Cartagena.

“He was really, really close to being my brother,” Gross said. “I don’t have a brother, but we loved each other. His contribution to society was immeasurable.” He said the young people who live in the Manton Heights and Hartford Park housing projects will especially feel Cartagena’s loss. He spent endless hours meeting, speaking and mentoring young men in those projects and trying to convince them that violence was not the solution to their problems.

Gross said that everyone — school administrators, politicians and the police — was charmed by Cartagena and the way he could connect with people from all walks of life. Last spring, Cartagena accompanied Gross to Guatemala for a conference on gang violence, and they mingled with foreign dignitaries including an ex-president of Guatemala.

“Everybody liked David,” Gross said. “He was so committed to his work. He formed relationships.”

THE TURNAROUND in Cartagena’s life was remarkable. Court records show that, as an adult, he had been arrested 15 times for crimes such as drug possession, breaking and entering and resisting arrest. One time, he escaped through the roof of the police station at LaSalle Square.

Gross said Cartagena told him he had “harmed and hurt” many people during the course of his life.

In 2005, someone told Gross that Cartagena might be a good fit for the institute. At the time, he was out of jail and working as a janitor at a bank in the city. After some coaxing, Cartagena submitted a neat, handwritten resumé to Gross, who said it was the first and only time he had received a resumé that was not typed. Cartagena was hired.

Cartagena was passionate about setting troubled youth on the right path. He was a powerful speaker who had credibility, as a former gang member and criminal, to connect with the kids. Keith Morton, a Providence College professor who serves on the institute’s board of directors, said it will be difficult to replace Cartagena and his contacts on the street. He’s also concerned about rising tensions among gangs across the city.

Last week, two members of the Dark Side Rascals were arrested for allegedly gunning down a member of the Asian Outlaw Boys.

Last December, at the institute’s annual Christmas Party, a black-and-white photo essay about Cartagena’s life was shown on a screen. Cartagena narrated the powerful presentation that a student from the Rhode Island School of Design had put together. The presentation showed how far Cartagena had come. Providence police Sgt. Michael P. Wheeler, head of the department’s Gang Intervention Unit, had once chased Cartagena, then a rising criminal, through the streets of Olneyville. He had grown to like and respect him. He was shocked to learn of his death.

“That’s awful,” Wheeler said. “I think David did a very good job. He did everything he could do to help people.”

— With staff reports from Gregory Smith

bmalinow@projo.com