As Malloy says, the US Marine Corps was based on the British Royal Marines, who trace their origins back to the reign of Charles II and the formation of the Duke of York and Albany's Maritime Regiment of Foot on 28th October 1664. (The name "Marines" first appeared in 1672.)
The US Marine Corps began on November 10th 1775; before there was a US, and the Americas were still technically under British rule. (Showing that the US Marine Corps really has been "semper fidelis".) As the American colonists were almost all British, they stuck with what they knew, and in preparation for war with England, it was the smartest choice to have a force which was the rival to the British's elite troops, ie, the American Marines.
The body had been in the hot tub for a while, so the skin would have become shriveled and would affect the fingerprints, thus when put on the fingerprint reader it would not have found a match.