All of the mustelidae are known for wanton killing, one of the reasons that ferrets had to be licensed in NYS for a while.  But there would not be an old saying about the fox in the henhouse if that were not also true.  I like Fisherladies idea about the sand trap, get an idea of what the opposition is.  And maybe check with DEC they may have some advise.

Set up a number of infra-red trail cameras at strategic locations.  You'll get an idea of what's frequenting the area.

Electric around The bottom at 1,3,6 inches. Will get The weasel traps built and a few snap traps and live traps set. Hope 600 volts frys the sumbirch

Weasel tastes like chicken.

Time for you to set up a poll. Animal and date of capture and/or kill. Winner gets 50% you will get enough $ for new chickens. 

went to get the mail at dusk and had a confirmed sighting of a fox. It was 100 yards down the road, but close enough to know it could smell chicken.  Now I am still thinking weasel due to the middle of the day thing but..........      
Traps are baited and set. 

Fox is my call . We see them here during day and my cat had many battles with them.
They mate in spring at night and sound like a child in distress . Ever hear that ?

Update ?

HT I've heard the cry of the Fox and  Yotes too, bone chilling at certain times.  Add the calling of the Sand Hill Crane and it's time in Jurassic Park.  lol
 
Got my fingers crossed for Clint, hope he whacks the culprit(s).

No updates yet, but the fence ad hot wire have kept all safe. Tonight I set some weasel traps ad live tras baited with some drumsticks that were on sale