This spring, Pennsylvania State Police were able to identify the remains of Corriveau and are now seeking the public's assistance in solving the cold case.
"He was matched through my DNA," said Cleary, 58, of Conway, N.H.
On Nov 18, 1968, the same day the 20-year-old Marine from Lawrence, Massachusetts disappeared in Philadelphia, an unidentified man was found dead alongside the Pennsylvania Turnpike near the Downingtown interchange in Chester County.
He was stabbed once though the heart and covered with a Navy Pea Coat. He became known as "Bulldog John Doe" after the distinctive tatoo on his upper right arm.
With no identification, the man was listed as "John Doe" and buried at Longwood Cemetery in Kennett Square.
It would be days before the family even knew Corriveau was missing. Cleary recalled how her father, a deputy sheriff, called the hospital to see if her brother would be coming home for Thanksgiving only to be told he was A.W.O.L. - away without official leave.
"We were pretty sure he was not alive," Cleary said. "If he was, he'd be home."
Corriveau grew up in Lawrence, Massachusetts, and was known as Bobby Dan to his two younger brothers, Paul and Tom, and his little sister, Virginia. He called her Gigi and he loved to tease her.
Cleary remembers Corriveau as being an excellent athlete who loved to play baseball and hockey. Incredibly smart, he attended Mount Saint Charles Academy, an all-boys boarding school in Rhode Island.
He enlisted in the Marines at age 17 and received orders to leave for Vietnam.
Corriveau served two tours. He fought with the Third Battalion, Fourth Marine Division, and was wounded in action on three separate occasions. He was sent home with two Bronze Stars, two Purple Hearts and a chest full of ribbons.
When he came home, Cleary taught her brother the latest dance steps.
"He didn't want to be square," she said.
But, Corriveau could not shake the flashbacks that came while he was awake and asleep, Cleary said.
Corriveau was first treated at the Chelsea Naval Hospital in Massachusetts. He was home on leave in October 1968, then traveled to the Philadelphia Naval Hospital to receive more psychiatric treatment.
On Nov. 18, the hospital staff reported him missing at morning roll call. He was on a locked ward, Cleary said.
"All these years, from 14 to now, I never stopped searching," said Cleary.
In July 2009 investigators from the state missing persons unit and the Chester County District Attorney's Office exhumed the body. A DNA profile was obtained through bone samples and entered into the national missing persons database.
Officials suspected the man had been in the military because of the tatoos and involved the U.S. Naval Criminal Investigative Service Cold Case Unit and the Marines.
On Dec. 5, Cleary received an "unexpected" call from NCIS asking about her brother's scars and tatoos. She was certain "pretty sure" they had found him.
NCIS would later visit Cleary to obtain her DNA and confirm the match.
Cleary wasn't done fighting. She insisted the Marines change the deserter designation and she had to go to court to get custody of her brother's body so he could be buried next to his father and brother, Paul, with full military honors."After 43 years we were shocked to find out what happened to him," she said of the murder. "And on the other side, we were happy that we finally knew."
Anyone with information, including those who served with Corriveau or who knew him from the hospital, is asked to call 610-268-5158 or email RA-1968MarineDeath@pa.gov.
Contact staff writer Mari A. Schaefer at 610-892-9149, firstname.lastname@example.org or @MariSchaefer on Twitter.