SAN JOSE, Calif. (KRON) -- A Santa Clara Valley Transportation Authority employee was angry about money when he allegedly killed his co-worker at a VTA bus yard in San Jose three days ago, investigators told reporters at a news conference held Monday afternoon. The homicide victim was Regulus Teotico, a longtime VTA bus operator and father of two teenaged children, according to VTA CEO Carolyn Gonot. "He was a kind, hard-working driver who was well known amongst his colleagues," Gonot said. A Santa Clara County Sheriff's captain said Teotico and his suspected killer, 33-year-old Duc Minh Bui, both worked as VTA bus drivers and were assigned to the Chaboya Division Yard at 2240 South 7th Street. Their workplace turned into a homicide crime scene after Teotico was fatally shot in the yard's employee parking area. Duc Minh Bui's mugshot was released by the Santa Clara County Sheriff's Office. Bui and Teotico were involved in "the same activities outside of VTA employment," including gambling, the captain said. "Money owed between the two from their betting activities" was the motive behind the homicide, the captain said. The shooting happened at 9:53 p.m. on Sept. 20. Sheriff's detectives worked around-the-clock to identify and arrest the VTA shooter. Less than 48 hours after the killing, Bui was arrested outside of his home and booked into the Santa Clara County Main Jail on suspicion of first-degree murder. Some VTA employees are still traumatized from a 2021 mass shooting that left nine of their co-workers dead. A mourner pauses in front of a memorial for the nine victims of a mass shooting at the Santa Clara Valley Transportation Authority (VTA) light rail yard on May 27, 2021 in San Jose. (Photo by Justin Sullivan/Getty Images) On May 26, 2021, a disgruntled employee opened fire inside a break room at the transit agency's Guadalupe Division building. The gunman, 57-year-old Samuel James Cassidy, fired 39 shots before he killed himself as law enforcement officers rushed into the building. VTA still faces a ‘monster’ after mass shooting, union leader says VTA memorial (File Photo by Philip Pacheco /Getty Images) On Monday, Sheriff Bob Jonsen acknowledged that the most recent shooting brings back concerns over workplace violence. Jonsen said, "This was a senseless crime -- without question. It's not lost on us that this incident brings back the memories ... where nine employees lost their lives. People need to feel safe when they come to work." VTA officials said, in addition to increased security from law enforcement, their employees have access to grief counselors and mental health support services. VTA Board Chair Cindy Chavez said, "After the tragic incident of three years ago ... for some people, this is re-living the worst experience they have ever had. Wrapping our arms around each other is so important." One of Teotico and Bui's co-workers said the homicide suspect and victim were close friends. At work on Monday, the VTA yard was so quiet that you could hear a pin drop, the co-worker told KRON4. Teotico was a fun person, full of energy, loved to laugh, and had a passion for food and cooking, the co-worker said. The Sheriff said he hopes Bui's arrest can help restore a sense of safety for the victim's family, the VTA's workforce, and the community. "A suspect has been arrested. This is the first piece of justice for the family," Jonsen said. Bui does not have a criminal record in Santa Clara County, court records show. He is scheduled to make his first court appearance on Wednesday. According to inmate records, Bui is being held behind bars without bail.