department of public safety trooper billy spears was disciplined last week .
the trooper posed with snoop dogg after rapper 's sxsw keynote speech .
snoop posted picture to instagram with the caption : ` me n my deputy dogg '
rapper 's past legal problems were cause for concern for spears ' superiors .
he was cited for ` deficiencies indicating need for counseling ' for photo with figure who has ` criminal background including numerous drug charges '