Haozi, while this recent young mother/teacher doesn't seem to fit (she was driving her car when last seen, she was found 6 days after going missing etc), the younger men seem possible to be connected. Not as in they know each other or even common people, haven't heard anything to the like. But they all were somewhat vulnerable at the time of disappearance, none have accessed their bank accounts, no positive sightings that have been confirmed, etc.
On went missing from our psychiatric hospital. They have since merged with our new general hospital but the old site was way up a highway, set way back from the road, treed in etc. He may have walked out to the highway but from there who knows. Another was from here but was about an hour away (up the same highway as the psychiatric hospital) at a cottage or something. He left angry after arguing with family and was thought to be hitching back here to go home. No hint that he might just be super mart about disappearing on his own accord, no confirmed sightings etc. Also it doesn't sound like the fight was something that would make him ditch his life, it sounds like how things happen with every family from time to time. His family has been tireless in searches, organizing dogs, helicopters, divers etc and although its been I think 2 years now they keep it in the news, keep his search alive via social media, etc. Another was from across the provincial border but was here in town visiting friends. He was last seen at a downtown bar. He was refused entry due to intoxication but his friend went ahead in and he was last seen leaving that bar to head a few blocks away to his friends. The second man I mentioned whose family is tirelessly continuing to search and find answers, when searchers were looking for him they stumbled on remains that ended up NOT being this young mans but rather a body left there even earlier than he'd gone missing. They have had no luck with DNA etc to match this body with missing persons in our country. The remains of this man were decomposed rendering cause of death unidentified but it does make you wonder. The second man that left the cottage after a family argument, some of his property was located in a wooded area but no sign of him or how his property got there. So many areas have been searched looking for him, that even with others missing, those areas do not possibly hold those others either. It is not easy to completely disappear a body as it looks in the movie. If something bad happened to them all, which it sounds like it did, it is odd that not one has had their body found. So if 4 separate killers were in our region it would be a statistical rarity for sure seeing as we have not a single unsolved murder here on the books. We rarely have any murders, years can go by. And the ones that occur are normally a mentally ill person turning on a loved one, or a matter of domestic violence. In my lifetime we've had only the following murders: when I was young a girl my age was killed (by my former downstairs neighbor), in my late teens a teen about 17 yrs old was killed in daylight in a short path cutting through a very small wooded area behind a mall on her way home. It took a few years but they caught the guy. Behind the mall is the bus station and he was wandering through and in between transfers did this to that young lady. There as a man killed as part of an organized crime thing, people were caught practically right away. I can't recall any other than these three, and I was born here. So something is up even if this isn't all done by one person. But it would make more sense for one person to be responsible than for mulitiple murders to occur so close together and all being younger men (20's) who at the time they disappeared were not at their best: one intoxicated and in a strange town, one wandering to a highway from a psychiatric hospital and one hitching on the same hwy while upset from a family disagreement. The fourth who knows. But obviously vulnerable person as otherwise he would have been identified via dental or DNA from the missing persons list. It's been probably 3 years since this man would have died (the state of body made it hard to decide how long since death) and still nobody putting out a call to find a missing loved one. Lends one to figure this person was on the fringe of our society, alone and without even a employer or landlord to notice a sudden disappearance.