Keller was born in Queenstown, Ireland Queenstown, County Cork, Ireland, in 1810 according to his grandson he graduated from Trinity College, Dublin but in fact Trinity College did not let in Catholics until 1970 and they had no record of his attending.
While in Guadalajara, he met Andrew A. Boyle, and the two returned to the United States — with Keller going at first to New Orleans, then to San Francisco in 1849 and finally to Los Angeles in 1851.
[2] Keller opened a general store at the corner of Los Angeles and Commercial streets and also purchased ten acres from Manuel Requena at Alameda and Aliso streets, where Union Station is now situated.
In addition, he experimented with various agricultural crops — fruit trees, castor oil plants, hops and cotton.
"[6] Keller was called the "father of horticulture in Los Angeles" because, as writer Stanley Gordon put it, "In 1853 he planted orange trees from seeds obtained in Central America and Hawaii.
"[7] Keller was an original director of the Farmers & Merchants Bank and of the Pioneer Oil Company.