The Post and Courier of Charleston reports Susie and Steve Polston were worried that someone was trying to get into their home on Sunday.
Instead, Polston's 16-year-old son found the intruder: a nine-foot alligator crawling on their second-story porch.
The family says the alligator climbed a back stairwell to the porch, crunched through the aluminum screen door and nestled between a sofa and a swinging bench.
State law requires a nuisance-trapped alligator to be killed, but the family didn't want that. The other choice was to wait it out, but the alligator was eventually euthanized. Last year, an alligator rang a doorbell, while another fell asleep on a porch.