She was in a mental health facility. She couldn't commit suicide.

Unless you mean at the time of the murders, in which case, she tried to commit suicide as well, but failed.

Various reasons.

Speaking specifically of insects -- the largest insects lived during the Carboniferous and early Permian. This is due to two reason. One is that oxygen content in the air was higher back then. Insects do not really have an advanced respiratory system. The second reason why insects grew to such large sizes during that time is because they lacked predators. They were the predators. Studying the history of insect sizes, we can see that the evolution of birds during the late Jurassic disrupts the relation between insect sizes and oxygen content. Even during times of rising oxygen, insect sizes remain smaller because when such a specialised group of insect hunters exists, being big isn't an advantage.

Now onto other creatures. Humans right now are bigger than we've ever been in our evolutionary history. We evolved from really tiny proto-primates, the size of squirrels. If we are looking just at our evolutionary history, we've grown tall. That said, there are limiting factors to being tall too in terms of physical health and resources needed. Humans are not very likely to grow much taller, because there is no real evolutionary pressure for us to do so. Often times in history when creatures have grown large, it was either to become a more efficient predator, or to become too big to be preyed on. But neither of those things really apply to us right now. We've shaped an environment in which our size doesn't really contribute much to our evolutionary success.

Now, as for other animals -- The age of dinosaurs really speaks to the imagination in terms of the size of creatures, but actually the largest creature to ever exist lives right now. In the ocean. The Blue Whale is the biggest thing that has ever existed on Earth. As for land animal sizes, Dinosaurs had some advantages that allowed them to grow that big -- hollow bones and airsacks means they were able to reduce their weight even when growing to enormous sizes. They still weighed massive amounts, but nothing like what any other animal would've weighted if you had sized them up to that size.

Right now, we do not have much surviving mega-fauna. And to be blunt, the reason for that is us. We are destroying the natural environment at a huge rate. While the change in climate at the end of the ice age had an effect on animal sizes (or more accurately, the extinction of several huge, cold-weather adapted animals), the way we are living now pretty much ensures that nothing as big as the animals that have once lived (except, again, the Blue Whale in the ocean, and we are threatening them too) is going to evolve again as long as we keep acting as we do. Being huge takes a lot of natural resources, and we aren't leaving any for anything but ourselves.

That's not exactly correct.

Only insect size correlates to oxygen content in the air due to the manner in which they breathe. However, oxygen content is not the only limiting factor in size. The Carboniferous and early Permian are when insects sizes maxed out. This is before the age of the Dinosaurs (who didn't start appearing until the late Triassic). Up to this point, insect sizes and oxygen content in the air is well correlated.

This changes during the Jurassic. Insect sizes dropped after the Permian when the oxygen content in the air dropped low. However, even when the oxygen content in the air started increasing again, insect sizes continued to diminish in size. Reason? Birds had started to evolve. With birds now dominating the air, and in many cases, preying on insects, being large no longer held the same advantages as it once did.

And again, this is just for insects. Other terrestial animals, such as dinosaurs or mammals were never limited in size by oxygen content. That's because we have a far more efficient way of breathing than insects do.

They absolutely retire sometimes.

The problem is that the ones that are continuously compelled to keep killing are far more likely to get caught than the ones that are able to have some control and go dormant. All our data was based on the ones that got caught, so for a long time, that was our understanding.

Now with genetic genealogy helping up solve some long-time unsolved cases, we actually learned that serial killers do sometimes just stop killing. The Golden State Killer famously did. After '86, he didn't commit any more killings. At that point, he was in his forties, so it wasn't even that he stopped killing due to an advanced age. Dennis Radar (BTK) committed his last murder in '91, but wasn't caught until 2005

Which is not relevant because DeRoos’ wife didn’t commit murder. She provided a false alibi/statement to the police which in most jurisdictions is only a gross misdemeanor.

Because evidence gets lost and degrades over time. Witnesses forget things and die. The longer ago a crime was, the harder it becomes to prove who did it (and to provide an alibi, which, while you are technically presumed innocent, is still important to keeping the wrong people out of jail)

Plus there is the more philosophical question of how long someone should be held responsible and if, at any point, it becomes less about correcting behaviour and more about vindictiveness. If someone committed a minor crime at age 17, and they are now 65 and have never once committed another crime, is society served by holding them responsible now? If prison time is supposed to reform someone (which is what many believe), does holding someone responsible for a minor crime they committed 40 years ago help anyone? Obviously there are crimes that are so immoral we should always keep people responsible (like murder) but for a lot of minor things, there is many people who feel that at some point it becomes irrelevant to prosecute.

It happened fifty years ago. The statute of limitations would've run out on that a long time ago.

Plus, there is always the question of if DeRoos threatened her too (he was obviously a violent man) and if you want to start prosecuting people who have made false statements under duress as that might lead to other people in similar situations never coming forward.

A lot of crimes eventually get solved because someone (usually an abused spouse) eventually goes to the police (most often when they've finally managed to get out of the abusive situation) and tells them they lied when providing an alibi previously. Yes, obviously they did something illegal at the time, but what is more important? Prosecuting these people for a relatively minor crime or being able to actually nail the people they were protecting at the time (who have often committed far more heinous crimes)

Feel free to produce evidence to prove anyone was harmed by this protest.

He is known to have a very domineering personality, and has previously held high positions in both the Supreme Council of Antiquities and then created Ministry of Antiquities. He's involved in everything in part because everything has had to go through him (or through the very small group he was a part of)

The things he has discovered or worked on are not fake. However, it is extremely hard for other people to independently publish or research things without his involvement. There has been criticism of this, though at the same time, others have said that his way of handling things has pushed for higher levels of quality VS what used to be there.