His whole career, Pomona Police Officer Greggory Casillas had worked up to this day: His last field training shift before he could finally ride solo.
The shift marked the end of his "ghost phase" of training, a two-week stretch when his training officer wore civilian clothes, mostly observing to make sure he was ready. Casillas told a co-worker that he could not wait to be on his own.
"He was so excited," said Allison Campos, a jailer with the Pomona Police Department. "He really wanted it. I've never met someone so eager to become a police officer."
Then tragedy struck.
During that Friday shift, a reckless driver led officers on a pursuit that ended with a crash. Casillas, 30, followed the driver into a Pomona apartment complex, where the man was barricaded in one of the units.
As Casillas approached, he was struck by bullets fired from behind a door. He was taken to a hospital, where he died. A second officer who was shot in the face trying to save him was released from the hospital and is recovering from his wounds.
The suspected shooter was arrested on suspicion of murder and attempted murder and is due in court this week.
More than 300 mourners gathered outside Pomona police headquarters Sunday night for a candlelight vigil, where officers wore black mourning bands with the number "16" — Casillas' badge number — over their badges.
"Losing Gregg has ripped a hole in the hearts of his family and members of this department," Pomona Police Chief Michael Olivieri said at the vigil.
Colleagues remembered the 6-foot-4 Casillas as a gentle giant, a hard worker who loved to joke around with and motivate his co-workers. A father of two small children, he was just starting to build a family with his wife, they said.
"He was such a go-getter," Campos said. "Never let anything, anyone bring us down."
The road to becoming an officer wasn't easy, but it was Casillas' long-term goal — and he earned it, his colleagues said. He joined the Pomona department in 2014, getting his foot in the door as a records specialist before working his way up.
"It was his dream to be a police officer," said Dawn Coday, a senior records specialist with the department. "It was happening, his dream was just beginning."
In the records department, Casillas pored over officers' reports, studying how to write them, as he hoped to do someday.
Later, he became a jailer, where he worked with Myra Williams, a seasoned jailer who has been with the agency more than 15 years.
"When he was training, he would want to do everything by himself," she said, recalling him saying, "'Hey, Williams, how do you do this? Show me, but don't show me.'"
Rowdy inmates, she added, would settle down in his presence. Last week, the last time she saw him, she joked with him, knowing he was so close to achieving his goal.
"Casillas, you're not done yet?" she told him.
"Almost, Williams, almost," he replied.
Campos, who also worked with Casillas in the jail, said he always carried study materials: Flashcards of penal codes, books to prepare for the police officer exam. He ate healthy, bringing home-cooked chicken and rice without spices to work, and stayed in shape so he'd be ready when he was accepted into the police academy.
"He was willing to do what ever he had to," Campos said.
Eventually, he got the email: a conditional offer to be a Pomona police recruit. He told Campos that he hoped he'd get an academy start date soon.
And he did. He graduated from the San Bernardino County Sheriff's Academy and was sworn into the Pomona police agency in September.
"He earned his spot," said Lt. Marcus Perez, whose godson completed the academy with Casillas.
As a supervisor who joined the agency 25 years ago, Perez periodically checked in with field training officers to see how trainees were doing.
When it came to Casillas, the answer was always the same: "That guy learns quick," Perez recalled trainers saying. " 'You only need to tell him one time, and that's it' — that's the kind of character he had."
Campos, who also always dreamed of becoming a police officer, is now more motivated than ever.
"He didn't get to do the job he wanted to," she said, through tears. "But I hope that I can make him proud."
10:35 p.m.: This article was updated with a statement from the police chief at the vigil.