San Francisco police release new clue after deadly hit-and-run of plant scientist

San Francisco police on Wednesday released to KTVU a photo of what is being described as a vehicle of interest in a hit-and-run of a young man, giving his family new hope. 

Thomas McKean's family came to the Bay Area from different parts of the country to honor his memory at places he loved.  

And they want answers.

"Sadness. Loss. For all the things  he could have done, would have done, should have done," said his mother, Tammy Alexander.  

On July 9 at 2:40 a.m.,  police said they responded to a vehicle crashing into a pedestrian at the intersection of 18th Street and South Van Ness Avenue in the Mission District. 

Officers arrived and found McKean, 28, suffering injuries caused by the collision.  

Police said there were vehicle parts left at the scene but nothing that could identify the car or the driver.  

McKean died at the scene.

"The lack of empathy to leave someone there suffering, it keeps me up at night ," said John McKean, the victim's younger brother.

Police said they don't have leads and haven't arrested anyone.

Now five months later, they released a photo of a light colored Honda that was in the area at the time of the crash. 

Police described it as a vehicle of interest.

McKean's family is now holding onto memories of him enjoying nature. 

This past Sunday, McKean would have turned 29. 

Family members came to the Bay Area from out of state to celebrate his life at Muir Woods, one of his favorite spots. 

John McKean said his brother was supposed to be his best man at his upcoming wedding. 

"Instead of him giving me a best man speech, I gave a eulogy at his funeral and that was something I never ever thought I would have to do," said John McKean. "We were planning to wear our suits for our wedding and not wear our suits for a funeral." 
 
Mom said her son was walking home after spending the day with friends shortly before the crash.  

He moved here two years ago to take a job as a plant scientist with a company that does indoor agriculture. 

His goal was to make a difference by feeding the world.

"What an impact he had on other people. I miss him," said Mom.

"We would be willing to forgive if the person did come forward and said I made this horrible mistake," said John McKean. 

He also said no one could replace his brother as his best man. 

The family is urging anyone with information to call SFPD Tip Line: 1-415-575-4444 or text a tip to TIP411 and begin the message with SFPD.

Amber Lee is a reporter with KTVU.  Email Amber at Amber.Lee@Fox.com or text/leave message at 510-599-3922. Follow her on Facebook @AmberKTVU,  Instagram @AmberKTVU  or Twitter @AmberKTVU.