PLEASANTON (CBS SF) — Four juvenile suspects were arrested Friday in the stabbing death of 19-year-old Jackson Butler of Pleasanton, including one suspect who had originally been arrested one month ago, according to police.

Members of the Pleasanton Police Department Criminal Investigations Unit executed arrest warrants on the four male juveniles Friday, taking three of them into custody. The fourth turned himself in at the station Friday, according to the police.

READ MORE: SportsLine Week 8 NFC East Picks: 'Everybody Is Piling On The Cowboys, And You Can't Blame Them,' Says Larry Hartstein

On April 22, 19-year-old Isaiah Joseph Howard was arrested in the case along with one of the four juveniles arrested today. The minor had been released to the custody of his parents pending additional charges.

“We discovered additional evidence which supported additional charges, the charge of murder and then also the charge of kidnapping during the commisson of a robbery, and that juvenile who was previously arrested was re-arrested today on those updated charges along with three other suspects,” Pleasanton Police Lt. Erik Silacci told CBS San Francisco.

The four underage suspects, who police said were all from the Tri-Valley area, were booked into Alameda County Juvenile Hall in San Leandro on the kidnapping and murder charges. Howard faces charges of accessory to murder and concealment/destruction of evidence and is in custody at Santa Rita Jail in Dublin.

Butler was stabbed multiple times in the parking lot of the Hyatt House Pleasanton Hotel on the night of April 15. The 2019 Amador Valley High School graduate was pronounced dead at a hospital later that night.

READ MORE: Gilroy Man Arrested For Fatal Hit-and-Run Crash After Nearly Year-Long Investigation

Police said Butler was was actively advertising and selling marijuana wax cartridges and the four suspects devised a plan to rob Butler of his product. Butler, who was staying in a room at the Hyatt House, went out to the parking lot to meet with people and a physical altercation ensued as the suspects robbed him, which ended in the stabbing.

Silacci said the investigation was still ongoing and other evidence is still being uncovered.

“We’re still in the early part of the investigation as far as we’re still getting returns from some of our search warrants, still going through evidence and processing evidence and we still have a lot of work ahead of us, but the case will be sent to the district attorney obvioiusly because there will be an arraignment in the next few days.”

Due to their age, police said the department would not be releasing any further information on the latest arrestees.

“The Pleasanton Police Department would like to extend our condolences to the Butler family. During their time of grief, they remained resilient, and trusted in our department’s ability to solve this crime,” a statement from the department said. “We hope the arrests and pending charges of these violent suspects will bring some form of closure to the Butler family.”

MORE NEWS: COVID: Alameda County Latest To Ease Indoor Mask Rules In Fully Vaccinated Offices, Gyms

The homicide was the city’s first in nearly eight years.