When a big rig collided with a car while changing lanes, it sent off a series of crashes resulting in the death of a Riverside father who was driving his motorcycle along the 60 Freeway on his way home from work earlier this month.

But the driver of that big rig never stopped, and on Friday, the victim’s family made an emotional plea for the public’s help in finding him or her — with the offer of a $5,000 reward.

Around 8 p.m. on July 10, a Toyota Corolla was driving eastbound along the 60 Freeway in the area near Diamond Bar and Walnut when a red big rig shifted into its lane and slammed into it, California Highway Patrol officials said.

That caused the Toyota to swing into the lane on its other side, crashing into another big rig, as CHP Lt. Kelly Moore explained at a news conference.

Then, the Toyota ricocheted across all lanes of the freeway, smashing into the center divider and then hitting 39-year-old Daniel Gutierrez on his Harley Davidson, Lt. Moore said.

The lieutenant said CHP has determined that the big rig driver did cause the crash, based on witness accounts and evidence including damage to the vehicles involved.

Witnesses said the big rig exited at Grand Avenue along the 60 Freeway, going toward Valley Boulevard as it fled, Moore said.

Gutierrez was the only person who died in the four-vehicle crash. It was just three days after his 39th birthday, his wife said.

“My husband was just a wonderful, amazing husband and father and he didn’t deserve for this to happen to him — especially (for) someone who caused the accident just to leave him like that and not have any compassion or care about it,” Gutierrez’s wife, Delilah, said.

The driver of the Toyota also suffered injuries, Lt. Moore said.

The big rig is described by CHP as an older model freight-liner with a red tractor and trailer, but there’s no license plate information available. CHP has not released any information describing the driver, including gender.

Moore said investigators have not gotten any follow-up tips on the suspect vehicle, and without the public’s help, the process of finding it is “like finding a needle in a haystack.”

“He knows what he did. There was damage to his vehicle,” Don Gutierrez, the father of the victim, said of the big rig driver.

“We want him to turn himself in,” he said. “And there’s other people that saw this big rig somewhere.”

Gutierrez was driving on his way home from a 14-hour shift as a heavy equipment mechanic who was part of a Southern California engineering union, his father said. As a father of four, he was the family’s sole breadwinner.

“Every picture he’s in, he always had a smile on his face,” his father said. “And he was a religious man.”

The victim’s wife said he called her just before he was leaving work, and she told him dinner would be ready when he got home. She said he would only occasionally ride his motorcycle home from work in L.A., other times driving instead.

“On top of the pain that we’re feeling, it’s the frustration of having no closure,” she said, standing alongside the couple’s four children and her own son and daughter-in-law at a news conference.

“Life is just never going to be the same,” she said.

Along with the offer of a $5,000 reward for information, she made an emotional plea for the driver to come forward on their own accord.

“If the person could just have a heart and just come and talk to the CHP, give their side of whatever happened – we would appreciate it.”

Anyone with information can contact the Baldwin Park CHP office at 626-338-1164.