Missing Newt?

Hi everyone. I've been away for work so far this summer. I left my two firebelly newts with my parents. They came to visit me, our dog-sitter watched over the newts for about a week. I came home yesterday and one of my newts is missing. He's the bigger of the two (about twice as big as the other one) but is not particularly adventurous. I cleaned the tank yesterday and there were no signs of newt remains. The pet sitters (who are very honest and trustworthy) said there was no sign of any of the dogs getting into the tank (lid was properly in place, lights were on and working, etc.). I do have a filter with a tube leading out of the tank, but the hole in the tank lid is very tight-fitting and I can't imagine that he would be able to climb out through that. Does anyone have any theories on what could have happened? I searched the whole room and didn't find him anywhere.

Well, I'd say he escaped somehow. Newts can force their way through surprisingly small holes or cracks and I think you would see it's remains if had died in the tank.
The only other thing is if it got out during a tank maintenance. Could he have been accidentally taken out with tank decor? I've nearly lost newts that were caught up in plants I've pulled out of the tank, I've even siphoned them out with the waste water and not noticed until I was tipping it away.

I just have a hard time imagining him escaping...he just sat on his favorite log all day. The other one is the curious one. If he did get out, is there any way he's still alive? Also is there a reason they escape, like if they don't like their tank or something?

One of my fire bellies got out, I searched high & low. Couldn't believe he could've gotten out. Some how the little bugger did, I looked all over for him to try & save him but unfortunately, the little guy was away from water too long & passed. It's a hard thing to face, but more than likely, your little guy found a way out & I'm not exactly sure how long they can survive without water, but I wouldnt say over a day but it could be less time than that. :'( Sorry to hear that