I've decided to embark on an expedition to further research the generation ships and maybe, arrive at a more in depth conclusion into some of their fates. It is the goal of this commander to find more of these ships as well.
Artemis seems to be a bigger, longer range ship than some of the other known models. She has to have had a bigger compliment, perhaps 20,000 souls or so. She has 6 biodomes, 4 of which are farm domes, two tree biomes or "park domes" leads me to conclude this ship had a large compliment, and likely enough supplies to sustain a long voyage. Their final destination is also unclear, I found a couple of systems with habitable planets within 20-35 ly from her final resting place at Mu Cassiopeia 3-1. One of which is an earth like planet. That planet would have put her destination around 50ish ly from earth. Seems unlikely they would send a ship this well appointed on that short a voyage unless:
1) This ship was sent as a reinforcement to an existing colony, or to a planet another colony ship had been previously dispatched to.
2) This ship was carrying a larger population on a shorter duration mission, perhaps under 75 ly. This would explain why 4 of the ships 6 biodomes are utilized for farming. It was needed to sustain a much larger population.
Which makes her fate that much more tragic.
From what can be gleaned from the intact logs downloaded, for those of you unfamiliar with these derelicts, there was an attack on board attributed to a dog that was snuck on board. This must have been very early on in the first generations voyage, as most dogs don't live more than a quarter century tops. At sublight speeds between .2c and .5c, that doesn't put them very far from home. The ship is presently less than 40 ly from sol. A crew member gave the location of the dog and when found, the dog was where it was supposed to be. No blood on it, didn't act aggressive.
That's where the other logs take a decidedly darker turn.
Another unidentified person began leaving dark, ominous recordings speaking in parables and referring to the ships compliment as "sheep" and himself the "shepherd" but in a way that leads you to conclude this person likely had a severe, undiagnosed mental illness that he either hid, or developed shortly after they departed sol. Either is possible. Deep space does funny things to your mind.
The last recording is Mr. Ominous spouting his typical dark rhetoric but this time, clanging can be heard in the background. Like a heavy tool smashing something electrical. A control panel, generator, who knows. Alarm claxons are blaring in the background. Then he spouts off about silencing the people. Then what sounds like an explosion. Then silence.
I conclude he must have irreparably damaged something critical. Life support wouldn't have been enough. There would have been enough atmo for the crew to attempt repair, or at least leave a final message. It seems more likely he destroyed something related to the main power plant. Whatever it was, it was catastrophic and final. The officially excepted explanation is that he damaged the main power plant, and that seems likely to me as well.
After studying the logs and picking as much information from them as I could, I postulate the killer was quite possibly the Captain himself. He was very quick to blame the mauling on the dog even though the evidence pointed elsewhere, and call it case solved. That seems irresponsible at best to end an investigation of this magnitude, and he was quick to do so.
After it became evident that the dog wasn't responsible, step one would be to launch a massive, full scale investigation to discover the killer. The person responsible would have had to either be a complete master of deception, or simply beyond scrutiny to have gotten away with terrorising the passengers for as long as he appears to have.
Also, there's how he finally kills everyone. Granted, we don't know a lot about how these ships were constructed but it seems to me, if you have a power plant that is all that keeps you and thousands of people from cold, oxygenless death, you protect the power plant. Double security doors, authorized access only area. While there are other possibilities, it seems most likely the killer already had access to engineering. So that would make him senior command, like the Captain, or engineering crew. I feel like a simple engineering crew member likely would have been discovered during an investigation, but who knows. That's my conclusion after studying what available information there is.