COACHELLA, Calif. -

We met Stacy Saenz, of Palm Desert, on Tuesday. She dropped to her knees in tears heartbroken, staring at the memorial setup for her co-worker and friend, 25-year-old Celena Marie Nava, of Coachella.

"She was just a big sweetheart, always with her big smile and everything," said Saenz.

Police said Nava, an employee at Eisenhower Medical Center, was walking along Calhoun Street near Avenue 49 with a friend on Sunday when they were hit by a white pickup truck.

Nava died at the scene. Her friend, whose name has not been released, was hospitalized with major injuries.

Officers arrested the alleged driver in the crash, 55-year-old Jose Jimenez that night near the scene. He was booked at the Riverside County Jail in Indio on suspicion of murder, gross vehicular manslaughter and DUI.

Jimenez is expected to be arraigned Wednesday.

"This didn't have to happen, it just didn't," said Saenz.

Saenz said Nava loved her friends, family, exercising and her dogs. The two were making plans to celebrate what would have been Nava's 26th birthday this Thursday.

"It's just so sad we can't be with her in person. I have to come visit her here,” said Saenz. “She was a big sister to me. I just loved her."

As for the man behind the wheel, Saenz can't comprehend the damage caused.

"I have no emotions toward him. I just ask 'Why?'" she said.

Saenz said she plans to focus on remembering the good times spent with Nava.

"I'm just going to miss her way too much. My Celena, always smiling," she said.

A memorial service for Nava will be held at 10 a.m. at Forest Lawn Mortuary in Coachella Sunday.