The "ten square leagues" of the rancho was granted July 11, 1846, by Governor Pio Pico to Tomás Herrera and Geronimo Quintana, both originally from Nuevo Mexico.
[4]: Appx, 42 Their title was declared invalid, because it was dated July 11, 1846, four days after the conquest of Monterey by the American Forces.
On May 12, shortly after they settled in the ranch house on San Juan Creek, it was the subject of an infamous attack by eight of the bandit gang of Jack Powers and Pio Linares that resulted in the robbery and murders of the two men and the kidnapping of Andrea Baratie, the English/Chilean wife of Bartolomé.
They were to have been murdered where their bodies could not be found, however Pio Linares did not remain to oversee the execution of his plan but returned to San Luis Obispo.
Murray and others in the town and surrounding ranchos organized a Vigilance Committee in San Luis Obispo County.
[4]: Appx, 42 The reason given for the failure of the grant case, was a failure to prosecute the case, but Walter Murray in his letters to the newspaper San Francisco Bulletin in defense of the actions of the Vigilance Committee, says the Frenchmen were there intending to purchase the grant: "Old ranches were changing owners.
A respectable Californian named Castro, from Santa Cruz County, had purchased part of the rancho of San Geronimo.
No others were found after their deaths to lend money to the grantees or buy the land from them and carry it forward themselves in the Southern District court.
Over the past seven years, with determined persistence, the Stephenson's have reassembled a substantial amount of the original San Juan Ranch.
It is the Stephenson's desire to reassemble San Juan Ranch in its entirety and preserve the property's rich and historic livestock production.