I wish CIC would give out updated information in the letters they send, the number they provide for the SSP in Mexico City does not work. Here's the link from the CIC letter we got about the SSP Certificate: It refers to the Certificate as "constancia de antecedentes no penales"
http://www.pgjdf.gob.mx/temas/1-4-1/index.php?tema=Antecedentes+Penales&idw3_contenidos=9
Here's the link to the one you can get in GDL
http://tramites.jalisco.gob.mx/infoTramite_hac.php?id2=972
If anyone knows if there's a difference between the two please post, I found pictures of the DF one and it looks exactly like the one my wife got in GDL, we can't get anyone on the phone except a pre-recorded message.
EDIT: Full link to the process in GDL the first one doesn't have the full details