At 5:40 p.m. on June 9 someone shot and killed Lewis in the parking lot of the Hillsdale Mall. Three months later, his friends and family are asking shoppers for help in solving the murder.
"This is the time of day it happened and its busy here. It's almost impossible for a car to shoot someone without someone noticing," said Viki Smothers, the victim's friend.
But very few people are talking and that's exactly what investigators say they need to solve this case.
"That's what makes cases like this the most difficult, when you only have a suspect and a victim and you don't have a lot of witness information," said San Mateo Police Sgt. David Norris.
Police are calling this case a high priority. The city's police chief also passed out flyers.
There have been 25 search warrants have been issued and hundreds of interviews conducted, there is even a $50,000 reward offered, but still no suspects and people are frustrated.
"I'm not trying to blame it on police, but we don't know, they're investigating, they say they're investigating, so we have to put it in their hands," said Lewis' son, David Lewis Jr.
"We have a whole police department that wants to help find progress and bring this individual to justice for David," said Police Chief Susan Manheimer.
The one who wants this case closed most is Lewis's widow, Margaret Lewis. She visited specific stores, including his favorite one.
"My stomach is really in knots, I was really indecisive if I wanted to come back to the scene of the crime where my husband was murdered, but I need to be here," said Margaret.
It's a sentiment shared by many.