Notarios in Mexico ate very different from those in the US and they do not certify signatures. Here the title Notario means they are educated abogados, attorneys, and have extensive training in transferring property ownership. In fact they are the only ones that can effectuate the transfer of real property in Mexico.
Notaries in the US can only , legally , certify a signature within a certain predefined area, maybe a County and only in the US. There was a guy saying he would notarize a signature here in Penasco but it would not be legal. I believe there is a US Notary in Ajo.
I found Notary Daniela Manzo Torres, phone 638-388-5255, who has an office in behind Bryan's restaurant on Fremont. She notarizes signatures the same as an Az notary would if you signed in Az. She speaks decent English.