Well, one of the transactions involves a parcel #APN073-112-013. When I entered that number at the link below, it came up Elm Street.
The Garrido property is APN051-072-0071. Here's the link to the assessors office:
https://taxcolp.co.contra-costa.ca.us/taxpaymentrev3/summary/controller_pyr.jsp
None of this may amount to a hill of beans, but I thought I'd put the info out there if someone who's more familiar with this stuff wants to check any of it out.
You can search it further here
http://www.ccmap.us/gis/
and, if this is correct, here is more on it (on Google maps it also want to call it Bay Point not Pittsburg
http://www.realtor.com/property-detail/1384-Elm-St_Pittsburg_CA_94565_2f66af01