Need Sherlock's Number, or perhaps Ms. Drew

I love a good mystery. At least the kind you can read about at your own leisure. I 'm not as fond of a mystery in my own day. Today I have a mystery. Timeline presentation:

Wednesday
4:30pm - sheep galloping all over kingdom come, breaking boxwoods, need to go back to barn.
              Middlest puts in sheep while I take other two to piano.
5:30pm-take Middlest to piano, pick up other two
6:00pm-eat quick dinner of meatloaf (made by youngest) and a sweet potato for me
6:30pm- two eldest to town for a 4-H training session
9:00pm- return home. While I was gone with two eldest, Huz and Youngest had reportedly done the chores in the barn, fed, watered all animals and collected eggs.
9:30pm- I go to bed, not checking the barn....

Thursday
5:45am-Middlest goes to barn to do first round of chores
Between 6:15-6:45am- Eldest and Middlest come say goodbye and leave for school
8:10am- I go to barn to do last morning chores. I enter the barn, letting out ducks and the gander. Upon opening the grain bin, and the horse grain can, I discover the grain scoop, which I fill for Olso.
I go call Oslo, who stops to water the paddock on his way to his stall. I note that there is about 1/4 of his hay left on the ground. He enters the stall, greets me, and then sniffs his feed, nibbling a bit. I notice this, and take the feed away, now suspicious that something is up as a horse who isn't hungry is potentially a very sick animal. I now note that Peaches also has unfinished hay. Now more observant I look around and note a large Oslo horse poop in the middle of the barn floor, outside the stall. Also, the bale of hay that had been tossed down from the loft last night is in a disarray, spread around and mostly eaten. Uh-oh, Oslo has definitely been out of his stall. I return the grain to the bin, looking for clues. I go through the door from the main barn into the poultry barn, the location of the grain bins. Ah-HAH! Another clue, there are several smooshed piles of horse poop in the area of the hose reel, including a bomb right on the bottom curl of the hose. Now, the mystery has turned dangerous- could the horses have gotten out of stalls, through the door to the poultry barn, opened the grain bin, taken the lid of the cans and been in the grain? I look inside the bins. All lids are in place. No bins are empty, but they are not full either, and I'm not sure exactly where the levels were yesterday. Back to the horses to check them. They are seemingly bright, alert and non painful. Peaches is nosing around in her hay. Gut sounds are audible in all four quadrants of the abdomen on both horses, hooves are not hot. I need to leave for work. I double check stall doors and go.
8:30am- phone Huz at work. He states that Youngest fed the horses last night, but Huz did not check to see if stall doors were latched before leaving the barn for the night. Also, he was the one that put the hose on the reel, so the poop on the reeled hose happened after he closed up the barn for the night.
Since Middlest did not mention the horses even being out of their stalls, I  am worried that I don't know if they were in the grain.
8:35am-call middleschool to talk to Middlest. She states that the horses were not out when she went to the barn. That they were in their stalls, and the doors were latched when she arrived at the barn in the morning.
8:45am- call neighbor and ask him to walk over to the barn and have a look. Could there be an open door into the barn from the pasture other than stalls? There are 3 other doors that would give access to the main barn.
9:15am- neighbor says all is normal, no visible way for horses to get into the barn at this time. Both horses in paddock, both standing.
So.................bumbadadah..........mystery.
They still seem to feel fine, although they have worked hard all morning grinding mud into their coats from yesterday's  thawed snowfall.

Upon cross examination, Middlest now thinks that perhaps Peaches stall was closed but not latched this morning..... I don't need Sherlock H. Drew, I need truth serum.