That's the problem with poison, they eat it and curl up and die somewhere else later so the dead ones smell bad for weeks afterwards. We use a 12 gauge short barrel shotgun and salt shells but I'm not sure it would be appropriate if you've got neighbours.
Ooohh,you and your liberal firearm use legislation....this is what we have to deal with; If i load salt into a shotgun cartridge,and any part congeals into a particle,larger than .32 of an inch,i then need a firearm cert (NOT shotgun cert),to possess and use it...
...BUT,on the shotgun cert,i can have a deck gun,off a destroyer,smooth bore it,and use that....with appropriate shot filled cartridges...
It really is easier to send the rat a strongly worded e-mail...
And,i am surprised no one has mentioned re-homing the lady,until the rodent problem is sorted...she stands a MUCH bigger risk of contracting Weils disease,than any electrocution hazard...