The situation was a little different on my end. The reason I exterminated the local coyote den was because my backyard (at the time) was a local elementary school soccer field. The coyotes were becoming aggressive, and one attacked my neighbor. This is usually very rare for a coyote to attack, so I suspected it was a den of what is called "coydogs" or "dogyotes". These are coyotes that have bred with large wild dogs and they are EXTREMELY dangerous.
Coydog - Wikipedia, the free encyclopedia
It turned out that my suspicions were correct, because the coyotes I exterminated were larger than German Shepherds. They had no fear of human beings. They could easily drag a small child off in the woods and you would never find the remains.
The coyote that killed my dog did it very fast. Coyotes are very smart and they will study your habits and schedule. You will never see them as they are predatory nocturnal creatures. I was walking my dog, on a leash, it came out of nowhere - attacked me, my dog tried to protect me but by the time I got back on my feet - they were both gone.
But, I understand exactly how you feel about losing your friend. It took me a long time to get over my dog.
There was a singer from Toronto that was killed by Coyotes. Her name was Taylor Mitchell.
Toronto singer killed by coyotes - thestar.com