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A photo of Hiram Lawrence supplied during a press conference regarding the one-year-old's condition at Children's Hospital in Oakland, Calif. Wednesday, Dec. 7, 2011. Hiram, 1, was critically injured in a recent shooting in West Oakland. (Family photo)

OAKLAND -- The three people allegedly responsible for the death of a 23-month-old boy after they shot into a crowd filming a rap video in West Oakland last year are members of a decades-old gang that has been responsible for dozens of murders over the years, authorities announced Friday.

An Acorn gang veteran and two younger members, including a teenager, allegedly killed Hiram Lawrence Jr. on Nov. 28, 2011 when they shot into a group of people they believed were members of a rival gang, federal and local law enforcement officials said. All three men are in custody.

"We're excited that they are prosecuting someone but it doesn't change the pain," said Annette Jointer, Hiram Jr.'s aunt. "We're still hurting and we're asking for support because we would like to see them get prosecuted to the full extent of the law."

Hiram Jr. was shot in the head as his father, Hiram Lawrence, held the boy near a taco truck in an attempt to shield him from the barrage of bullets that rang from guns being fired by Dionte Houff, 30, Houston Nathaniel III, 23, and Fredrick Charles Coleman, 16.

Oakland police struggled to solve the case but with help from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the U.S. attorney's office, leads were strung together and charges finally filed this week against the three gang members authorities described as three of Oakland's "most dangerous" individuals.

"It was a complicated, sensitive and emotional investigation," said Oakland Police Chief Howard Jordan. "We will find our most violent offenders and remove them from the streets."

The joint investigation into the killing resulted in separate criminal cases against the three alleged killers. Houff and Nathaniel were indicted Thursday by a federal grand jury on numerous federal felonies including racketeering, murder, attempted murder and assault with a deadly weapon.

Nathaniel was also indicted on federal charges of attempted murder in connection to the shooting of two teenagers in separate incidents on Nov. 6, 2011.

Each could face the federal death penalty at the maximum and life in prison at the minimum.

Coleman, who authorities said was the person who fired the bullet that killed Hiram Jr., was charged in state court as an adult with seven felonies including murder and attempted murder. Each of the charges filed against Coleman includes special allegations that his crimes were conducted to enhance the Acorn gang. He faces life in prison.

Alameda County District Attorney Nancy O'Malley said Coleman was charged in state court because it is harder to charge juveniles in federal court as adults.

Local authorities said the case could not have been solved without the help of the federal government. It's a partnership that has grown closer, officials said, as Oakland struggles to stem an ever-growing plague of violent crime.

"We have to try to help," said Melinda Haag, the U.S. Attorney for the Northern District of California. "As a result of gun violence, as a result of gang violence, five children were shot (by these three people) in Oakland and one of them died.

"This has got to stop," Hagg said.

Authorities refused to release details Friday about how the crimes were eventually solved. In court documents filed in the Coleman case, an Oakland police officer said surveillance and other videos helped police identify the three alleged killers. The officer, Eriberto Perez-Angeles, also said in court documents that witnesses identified the three as members of the Acorn gang.

Jointer said the Lawrence family was not given details of the arrests but she said the family is grateful that law enforcement continued to pursue the case despite troubles early on.

"We hope they continue to pursue it but there's no relief, the baby still isn't with us, we are still struggling and mourning every day."

The Oakland Police department is also struggling to find a way to shutdown the Acorn gang.

The gang's involvement in the killing of Hiram Jr. has forced Jordan to re-evaluate his department's approach to defeating the criminal enterprise less than two years after the Oakland Police Department boasted it had "disrupted" the gang with the attempted murder conviction against its then leader Marc Anthony Candler.

That conviction stemmed from a 400 officer, 17 agency operation against the gang dubbed "Operation Nutcracker" that resulted in the arrests of 54 suspected Acorn gang members.

"We didn't get everyone, we couldn't remove all them from the streets," Jordan said Friday of the gang. "We constantly have to monitor, we really need to have a maintenance plan."

Scott Johnson contributed to this report.