Twelve years ago, the body of a young government lawyer was found along the banks of the Potomac River. For years, police thought it was likely that Joyce Chiang committed suicide. Now, her brother said, police think she was killed.

Roger Chiang, who was living with his sister when she disappeared from the Dupont Circle area in January 1999, said he has been briefed on the case by two D.C. homicide detectives and a prosecutor. Chiang said he never believed that his sister had taken her life.

“The clouds have been lifted, and the truth will be spoken,” Chiang said. “All these years, we’ve been fighting for the truth to come out, that Joyce did not commit suicide.”

Chiang said he plans to appear with D.C. Police Chief Cathy L. Lanier and John Walsh, host of “America’s Most Wanted,” at 10 a.m. Friday in front of police headquarters to announce the developments in the case. He said he was told that there are two suspects.

Lanier’s spokeswoman, Gwendolyn Crump, would only confirm that Lanier will speak Friday about the case.

Joyce Chiang, who worked as a lawyer with the Immigration and Naturalization Service, was last seen near Dupont Circle on Jan. 9, 1999, when a friend dropped her off after dinner. The 28-year-old had planned to get tea at Starbucks and then walk to the apartment she shared with her brother. She never made it home.

The next day, a couple walking in Anacostia Park found Chiang’s government identification card. Her green suede jacket, keys and other items were later found in a grassy area just south of the park.

After Chiang’s disappearance, family and friends gathered Saturday nights in Dupont Circle to pray for her safe return. They posted fliers with her photograph around the area.

In April 1999, a canoeist found Chiang’s body along the Potomac in Fairfax County. An autopsy did not reveal the cause of death.

In 2001, police said Chiang probably committed suicide. But family members said they thought evidence suggested she was a victim of foul play.

Roger Chiang said he has spoken to Lanier and that the chief apologized to his family for the years in which the department thought that Chiang killed herself.

Roger Chiang said authorities told him that the two suspects in his sister’s case had committed a string of robberies around the time of Joyce Chiang’s disappearance. He said authorities told him that they believe his sister might have been attacked in Dupont Circle and been driven across the Anacostia River. She might have been pushed into the river or dove in in an attempt to escape, he said.

Roger Chiang said he first learned that authorities were reexamining the case in April 2010, when he received an e-mail from Amanda Haines, a D.C. prosecutor who works on cold cases. He said he met several times with Haines and Anthony Brigidini and Kenneth Williams, two D.C. detectives who specialize in cold cases.

Roger Chiang said he knew that authorities were making progress when they asked him about a specific detail. As children growing up in Chicago’s suburbs, Roger, Joyce and their brothers, John and Robert, were taught by their mother to put their feet into plastic bags before putting on socks and boots.

“They asked me if that was something that Joyce would ever do,” he said. “When you hear something like that, it’s a blast from the past to have that kind of intimate detail.”

Joyce Chiang graduated from Smith College, where she was student body president and was drawn to public service. She worked as an intern in the office of Rep. Howard L. Berman (D-Calif.) and focused on immigration law. She later got a job at the federal agency known then as the Immigration Naturalization Service.

Roger Chiang met TV’s Walsh while trying to drum up media attention and ended up working for him. He is proud to say that he has helped capture seven fugitives while working on “America’s Most Wanted.”

“I think the lessons is, you suffer tragedy but don’t lose faith. Keep hope because justice will come in some form or fashion,” he said.