I can't find anything that links Corporal Robert Daniel Corriveau to Betsy Aardsma apart from the way that they were killed and the timeframe. Given that there is nothing else on this cold case, I thought it best at least to comment on their strange one stab to the heart murders just one year apart in the same state.
It is interesting that you mention the possibility of a connection between these two cases. I know of both, but do not know of any connection between the two either - other than the odd coincidences you mention.
Both cases remain open and unsolved.
Here is a possible suspect in the Aardsma case:
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Richard Charles Haefner (deceased)
A 25 year old Geology student at Penn State University in 1969.
Haefner is considered a potential suspect/ Person of Interest in the murder of Graduate Student Betsy Aardsma.
Investigators consider him a person of interest in the Ardsma case due to his strange behavior before and after her murder, his later history of violence towards women, and a history of Pedophilia.
He had an explosive temper which led him into conflicts with police and others on numerous occasions.
Haefner was a resident of Lancaster, PA, which is only about 25 to 30 miles west of where Corporal Robert Corriveau's body was found.
Lancaster, PA is also not far from Maryland where two young girls disappeared in 1975. Three young girls disappeared from places in Pennsylvania which were not far from Lancaster.
On August 15, 1975, Haefner was arrested by Lancaster police and charged with corruption of minors and involuntary deviate sexual intercourse. The alleged victim was a 12-year-old boy who claimed that Haefner, who employed him and other youths in a small family business, had engaged in sexual contacts in a garage which was part of the business premises. Haefner denied the charges and over the course of several years, was exonerated of all wrongdoing via multiple mistrials.
In 1994, he again appeared before a judge for aggravated assault of a police officer and disorderly conduct. He was also charged with tampering with a witness and criminal mischiefpuncturing the tire of a 1989 Pontiac. The tool he used was a sharpened screwdriver.
Haefner died 19 March 2002 in Las Vegas, Nevada of a heart attack.