After finally finding the pole and the net, I removed the carcass from the deep end of the pool and do a gross examination.
Analysis. 
Genera/Species: Rattus sp. 
Sex: Male 
Weight ~500 grams
Age: Unknown
Coat color: Gray, red. 
Gross Pathology:
Rigor mortis
Rectal prolapse
Raised thoracic
Possible edema
Bulbous eyes. 
Cause of death: All indicators lead to conclusion of drowning. 
Awaiting veterinarian advisement
No necropsy was done.
Full disposal was implemented.
I am going to have Zombie Rat nightmares! I do not like rats like these. They carry Yersina pestis! Meanwhile, my husband is laughing at me because he is the vet! Wanted me to do a full work up necropsy! And there are several nodes as to how these pests enter my parents' domain! Fortunately, we have not see the droppings yet. But I would not be shocked to be the one to discover them! Usually I am and the one who has to deal with it.
Where are my parents? In Las Vegas! Partying!
Le sigh!

