OAKLAND -- Maria Climaco admits that she is still in shock over the killing of her only child two weeks ago.

Still, she found the strength to stand on the sidewalk Tuesday afternoon, holding a family photo and pleading for help finding the gunman who fatally shot her son and forever changed her life.

"Quite frankly," Climaco said, "it hasn't sunk in. The toughest part is waiting for him to walk through the door and ask what's for dinner. I miss him so much."

Aya Nakano was one hour away from his 23rd birthday when he was shot and killed at 11 p.m. on June 12. An unknown driver in a late-model four-door silver sedan rear-ended Nakano's Jeep Cherokee on Market Street near Stanford Avenue, and when Nakano stepped out of the Jeep to discuss the crash, an argument ensued and the man shot him, family and police said.

Aya Nakano, who was shot to death in Oakland, Calif., on June 12, 2013, celebrates his recent graduation from the University of Oregon. The Emeryville
Aya Nakano, who was shot to death in Oakland, Calif., on June 12, 2013, celebrates his recent graduation from the University of Oregon. The Emeryville resident would have been 23 on June 13. (Oakland Police Department)

A reward for information leading to the arrest and conviction of the two men involved in the killing has now reached $35,000. Nakano's uncle, Troy Aquino, set up a donation Web page for the reward, taking in nearly $25,000 in pledges. Crime Stoppers of Oakland is offering up to $10,000 in the case.

"I'm begging you with all my heart, please come forward (if you know anything)," Climaco said. "No one is out to get anyone. Just please help us find (who) did this."

Oakland police Officer Eric Milina, the lead investigator on the case, said damage to the bumper on Nakano's Jeep may reveal more information about the suspect's car. The case remains under investigation and police said Tuesday it's not clear if the crash was truly an accident.

"It's difficult to determine if this really was an accident or if this was a ruse, a setup," said police spokeswoman Officer Johnna Watson.

On the night he was slain, Nakano was returning to his home in Emeryville for a late dinner with family after playing pickup basketball at the recreation center at UC Berkeley. Watson said police have surveillance video showing him at various points on his trip from Cal to the scene of the crime in the 5800 block of Market Street. Some of that video still needs to be reviewed.

Nakano earned a degree in sociology from the University of Oregon last year and four of his college friends were at the news conference Tuesday. They are holding a benefit to increase the reward fund and help raise money to pay off Nakano's student loans. The event is from 4 p.m. to midnight on July 13 at Pedro's Cantina, 128 King St. in San Francisco.

Anyone with information on the case is asked to call Oakland police at 510-238-3821 or Crime Stoppers at 510-777-8572. To donate to the reward fund, go to http://www.gofundme.com/39z06g.

Follow Kristin J. Bender at Twitter.com/kjbender.