I will say I definitely am NOT a forensic genealogist (lol) - but I am working on my Forensic Psychology Masters degree, and have a 4-year Psychology degree as well as a 4-year Law degree. My specialization is mentally-ill offenders, aboriginal offenders, sentencing, and effective forensic treatments that avoid imprisonment for both of these populations.
If there's any way possible, get your DNA to MAINE, USA - starting with the closest jurisdiction to where your father was last seen in St. John's, NB. I would bother EVERY single level of police in Maine, and then move up the chain (including state troopers, even FBI if necessary as they have an excellent search team specializing in missing persons and may even have details other local officers do not, from another jurisdiction way off the mark, or perhaps even reports/incidents of finding John Doe's and are searching for a relative to notify), then taking more serious steps up the ladder given that you have already tried pretty much all you can do, in my opinion anyway. It is sad that we have to be our own defenders and protectors these days, my aunt is an unsolved homicide here in the city where I live, but the police keep switching the cause of death between suicide, homicide, long-term drug & alcohol abuse. The coroner's report is refusing to be released by the medical examiner on top of that! It's frustrating to say the least.
Canada is VERY different from the US in that our Privacy and Access to [Personal] Information laws are different. In Canada, the governments are clear and strict refusing to share any information pertaining to another individual or even to another governmental body or department. The laws in Canada actually PROHIBIT your "online DNA" sharing to be used against you in solving murders, missing persons, and other criminal cases; whereas, the USA does not have such a strict stance when it comes down to solving cold cases, murder, missing persons cases, and criminal cases in general. The USA is MUCH more liberal with the sharing and usage of "online DNA" and many of the popular family tree/genealogy websites actually have sneaky little clauses for those US citizens who sign-up that provide their CONSENT by clicking the check mark box and agreeing to the lengthy Terms & Conditions in that too small print that basically NO ONE EVER READS! Luckily, this too is prohibited to be utilized against citizens of Canada (the consent checking off part).
Once your "online DNA" has been shared and is out there on genealogy sites (like Ancestry, FamilySearch, etc.), the US governments/departments may use it for any criminal investigations they feel necessary. Canada does not have that liberty or overarching power, since we have strict Privacy and Access to [Personal] Information laws here, PLUS we are also blessed enough to be protected by Charter Rights as well.
It essentially comes down to simple state-jurisdictional differences in Privacy & Access to Info legislation and the one-sided Canadian Charter Rights. Think of it in a sort of way that is similar to how Canada has a common law system of law (innocent until proven guilty) vs. how the USA has an inquisitorial system of law (guilty until proven innocent)....The 2 countries laws are similar, but the details often vary in nature given the circumstances.
