Keira “Pooh Bear” Holmes was dead before her second birthday, gunned down in 2011 as she played in a courtyard of the B.W. Cooper housing development on the Sunday before Christmas.

The cover had yet to close on her tiny casket when New Orleans homicide detectives learned that the car used in the drive-by shooting belonged to Charles “Buck” Anderson.

A hotheaded member of the “3NG” gang, Anderson had gotten into a fight three months earlier that sparked the killing of Lester “Fat Man” Allen on Dryades Street.

So with Keira dead and police bearing down, the “violent enforcer” who had pulled the 9 mm trigger on Fat Man was taking no chances.

Washington “Dumplin’ ” McCaskill, along with another man, paid a visit to Anderson at a house on North Robertson Street the day after Keira’s slaying. They silenced their fellow 3NG gang member with multiple gunshot wounds, in what McCaskill admitted Friday was an execution.

McCaskill, 35, took credit for that killing, Allen’s slaying and that of a third man, Lester Foster, as he pleaded guilty Friday to three manslaughter charges along with a gang racketeering count and four heroin and cocaine counts.

Most of the allegations are contained in a wide-ranging gang racketeering indictment that Orleans Parish District Attorney Leon Cannizzaro’s office brought in 2013 against 20 alleged members of 3NG, named for their turf around Third and Galvez streets.

McCaskill wept in front of Criminal District Court Judge Camille Buras.

“I just want to apologize to the families for the guys I killed. That’s all,” he said.

He also admitted his crimes in a five-page “factual basis” that loosely connects two slayings that left the city rattled and outraged: Keira’s death and that of 5-year-old Briana Allen five months later as she sat celebrating a cousin’s birthday on her grandmother’s porch.

Fat Man, it turns out, was Briana’s uncle. During the same scrap, McCaskill also shot but didn’t kill Burnell Allen, Briana’s father.

The slayings of both children left the community shaken. Mayor Mitch Landrieu, who attended both funerals, later described Briana’s murder as a tipping point in the city’s resolve to address a jarring pace of murderous, often senseless violence.

Briana’s murder “shook the city into a position where it could not look away,” he said in January after three men were convicted in her killing, which prosecutors described as a misfired strike by the St. Thomas-area “110’ers” gang and two associates against a rival group, the Young Melph Mafia.

What followed the two killings was a series of massive state and federal indictments targeting what authorities have described as some of the bloodiest street groups in the city. The largest of those, in the number of defendants, was the 3NG indictment, which named 20 defendants in several murders and drug crimes.

McCaskill admitted Friday that he dealt heroin and crack and “was looked up to and respected by younger members.”

Along with the killings of Lester Allen and Anderson, McCaskill also admitted killing Foster on Nov. 23, 2011, in the 3200 block of Second Street.

Foster, 23, owed McCaskill money for heroin, the factual basis states. McCaskill also thought Foster and Fat Man were related and that Foster would retaliate for Lester Allen’s killing.

Ballistics tests linked one of the guns used to kill Anderson with the weapon used to kill Foster, the factual basis states.

Buras set a May 15 sentencing date for McCaskill. Each manslaughter count carries up to 40 years in prison, with a maximum of 50 years on the main gang racketeering charge.

His plea was the latest conviction in the 3NG case, which had sat largely stagnant for more than a year.

On Wednesday, Ronnell Owney and Tadaro Keller pleaded guilty to racketeering and other charges, with Owney getting a 20-year sentence and Keller taking 27 years.

Another defendant in the 3NG case, Quincy Briggs, was convicted in January of heroin distribution.

Authorities say many 3NG members also began identifying themselves as “106 and Prieur,” after their primary drug-dealing spot; the name was a takeoff on the once-popular BET show “106 & Park.”

Alleged 3NG members Tyrone “Biscuit” Knockum and Terrioues “T-Red” Owney are accused in Keira’s murder, while members of the group also are named in the high-profile 2010 killings of bounce rapper Renatta “Magnolia Shorty” Lowe and Jerome “Man-Man” Hampton as they sat in a car in New Orleans East.

Follow John Simerman on Twitter, @johnsimerman.