Parker Wayne was a Navy Captain who died of a heart condition four months prior to the events in "Head Case". However, instead of being cremated, his remains were used in an illegal chop shop specializing in selling human parts while some remains composed of ash and peddles were given to his family instead.
By pure chance, NCIS who were busting three sailors involved in the running of an illegal motor pool/chop shop came across Parker's head in the cooler of the back of a car and opened an investigation.
Leroy Jethro Gibbs visited Parker's widow, Jocelyn and daughter, Chrissy and received the pot containing Captain Wayne's ashes.
However, things took a turn for the worse when Abigail Sciuto discovered that the ashes were actually bogus.
After the investigation was closed and all the criminals were brought to justice, Parker's remains were brought back together, cremated and given to his wife and daughter who could fulfill his final wish of having his ashes scattered at sea by his former shipmates.