The parents of a US marine whose body came back from Greece missing his heart have amended their federal lawsuit to add the Greek government and an Athens hospital as defendants.
Craig and Beverly LaLoup are also suing the US Department of Defense over the remains of 21-year-old Sergeant Brian LaLoup.
LaLoup, who was assigned to a security detail at the embassy, had told a colleague he was suicidal over a breakup.
The parents believe a marine supervisor knew about his mindset, but instead of getting help, took him out for drinks.
Their lawsuit alleges their son was allowed to get a weapon from a storage area later that night, despite his mood and level of intoxication, and shot himself.
The US government is generally immune from wrongful death lawsuits, so the family is seeking damages only over their emotional distress caused by the missing heart.
They say they learned about the missing organ only accidentally, weeks after they buried their son. They also say they eventually were given a heart that wasn't his.
''This is his heart. This is his soul. This is what made Brian who he is,'' Beverly LaLoup said.
LaLoup, who was buried with full military honours, had previously served in Afghanistan and South Africa.
He died on August 12, 2012, at Evangelismos General Hospital, where an autopsy was conducted six days later.
The heart was found to be missing during a second autopsy conducted by US military officials on August 22 after the body arrived in Dover, Delaware.
The family only learned about the missing heart on September 17, two weeks after the funeral.
Christos Failadis, a spokesman at the Greek embassy in Washington DC, said the heart was kept for toxicology tests.
He declined to answer questions about what happened to it or why the family later received a heart belonging to someone else.
Pathologists say organs are often removed during autopsies for testing, but they said it would be unusual to use the heart, rather than blood or other fluids, for toxicology tests.