census info help

In researching my father I found a 1930 Mexico census on Family search with my grandmother as head of household but the residence is "Carcel Municipal de Guanajuato" I have pasted part of the information below. My question what does this mean? and is there somewhere to find arrest/jail archives? I am having a hard time finding birth record for both of my paternal grandparents :( so any help would be appreciated. Thanks!

Head of Household: Maria Luz Hdes
Residence: Carcel Municipal, Irapuato, Guanajuato, Mexico
Birthplace: Guanajuato
Marital Status (Spanish):
Film Number: 1464248
Digital Folder Number: 4107113
Image Number: 00078
Page Number: 21
Line Number:

Household Gender Age
Santos Zavala M 6a
Salvador Zavala M 1a