Importing sea turtles or any sea turtle product is absolutely and strictly forbidden by federal law. If they catch you with a real tortoise shell comb (made from a Hawksbill sea turtle shell) you will get a huge fine. There are no exceptions for private individuals, no special permits whatsoever. Any exceptions would result in various scams and fradulent activity so the ban is absolute.
If you can get a rescue designation and you have the required massive facility it's possible to have temporary custody of a sea turtle while it is recuperating. These are adult and semi-adult animals. Every fall volunteers scour certain beaches in New England where cold stunned turtles, mostly Ridleys, wash up after being carried north on the Gulf Stream. These are cared for at a designated facility.
Two years ago I seined up a yearling Green Turtle in New Jersey's Barnegat Bay and immediately released it. A long, long time ago, when it was legal, I raised a hatchling Hawksbill. I had it for 4 years before it got too large. I donated it to the NY Aquarium.
When I saw it flying through the huge tank they put it in I realized how selfish i was to have restricted it to a relatively tiny 150 gallon tank. These creatures belong in the sea. They are vanishing as their nesting beaches are turned into condominiums or flooded by rising sea levels.