Colorado Fugitive Edwin Ernesto Rivera Gracias Newest Addition to FBI 'Ten Most Wanted' List: Exclusive

March 14, 2013 — -- A man with connections to a violent international gang and wanted for the brutal murder of a Denver man will be the latest to join the ranks of the FBI's "Ten Most Wanted Fugitives" list, ABC News has learned.

The fugitive is 28-year-old Edwin Ernesto Rivera Gracias, identified by three law enforcement sources who would not speak on the record ahead of an official announcement planned for Thursday morning. Officials fear Rivera Gracias, who says he is from El Salvador, may have fled the United States.

MORE: 11 Facts About the FBI Top-10 Fugitive List

Rivera Gracias is wanted for first-degree murder in the stabbing death of 69-year old Denver resident Richard Limon. On Aug. 17, 2011, a cyclist discovered Limon's half-naked body on Lookout Mountain in Jefferson County, Colo. His mouth and nose were covered in duct tape, and investigators believe Limon was already dead when his body was thrown from the side of a mountain road, tumbling down a rocky slope through bushes and weeds. A broken-off blade from a steak knife was found lodged in his chest.

According to an affidavit written by FBI Special Agent Russell Humphrey, Rivera Gracias "expressed his desire to kill" Limon to an acquaintance about a month before Limon died.

Rivera Gracias was angry because his girlfriend told him that Limon had molested her as a child and had twice sexually assaulted her mother, according to an unverified claim in the affidavit.

With the help of another man, the affidavit said, Rivera Gracias allegedly attacked Limon as he was lying on a couch, wrapping duct tape around his nose and mouth as the victim called for help.

"After wrapping the duct tape around [Limon]'s head, [Rivera Gracias] began beating him about his face and head with his right fist. Between 10 and 15 minutes elapsed without [Limon] dying," the affidavit stated.

Rivera Gracias, the affidavit added, left and soon returned armed with a six-inch-long knife that he allegedly used to "rapidly" stab Limon five or six times.

"The final stab wound was to [Limon's] heart and resulted in the knife blade breaking off within his body," Agent Humphrey wrote in the affidavit.

After Limon stopped breathing, Rivera Gracias and another man allegedly wrapped Limon in a blanket and put his body in the back of a pickup truck for the drive to Lookout Mountain, the affidavit said.

Three acquaintances of both Limon and Rivera Gracias were arrested on murder charges shortly after Limon's body was found, but Rivera Gracias has been on the run ever since. Investigators believe he was using a cell phone that was traced to the Los Angeles area about two weeks after Limon was killed.

The FBI launched an international manhunt to find Rivera Gracias. A federal judge issued a warrant for his arrest in 2011 for unlawful flight to avoid prosecution.

Rivera Gracias claims to be a member of Mara Salvatrucha, a notorious street gang also known as MS-13 that began in Los Angeles and has roots in Central America. Officials said he has "MS-13" tattooed across his back and "503" -- the country telephone code for El Salvador -- on the back of his left arm.

MS-13 now operates in at least 42 states and counts between 6,000 and 10,000 members nationwide, according to an FBI threat assessment.

Today is the 63rd anniversary of the FBI's "Ten Most Wanted Fugitives" list.

Nearly 500 people -- all but eight of them men -- have been on the list since it began in 1950, according to the FBI. The first fugitive to make the list was Thomas James Holden, accused of murdering his wife and her two brothers in Chicago. He was captured in Beaverton, Ore., in 1951.

The last person added to the 10 Most Wanted list from the Denver region was Theodore Bundy, a prolific serial killer police believe was responsible for at least 36 murders.

Bundy was added in February 1978 after he escaped from a jail cell in Glenwood Springs, Colo. He was recaptured six weeks later in Pensacola, Fla., and was executed in 1989.

ABC's Jack Date contributed to this report.