One summer day, a cow and a steer walked away from their farm. The cow was black and was named Blackee. The steer was golden brown, with two stubby horns. He was named Hornee. Nobody knows when the cows got out, or how. They crossed a field and a road and wandered onto a neighbor’s yard.

This type of thing sometimes happens in rural western New York, where pastures and farms stretch for miles. But Hornee and Blackee had crossed not into another farm but into an animal sanctuary whose owner saves farm livestock from slaughter and encourages visitors to become vegans.

The next morning, Tracy Murphy, the sanctuary’s owner, found the cows in her yard. She herded them into a pen, she said, and immediately notified the local animal control agency. Six days later, an investigator with the agency came to check in on the cows. He interviewed people around the area and learned that a neighbor, Scott Gregson, was missing a heifer and a steer. Clearly, the cows discovered at the sanctuary belonged to Mr. Gregson.

But when Mr. Gregson asked that they be returned, Ms. Murphy refused. First, she demanded proof that Mr. Gregson actually owned the cows. She also demanded he pay $2,500 to reimburse the sanctuary for nine days’ worth of hay, straw and care.

Or, Ms. Murphy suggested, maybe her sanctuary could buy the cows, whom she was now calling Little Willow and Ismael.

That was two years ago. Since then, the case of the wandering cows has inspired death threats, rowdy protests, shadowy figures skulking in the woods, intercessions by Fox News and Joaquin Phoenix, stolen chickens, county and state legislation and a court battle featuring a rotating cast of lawyers, one of whom was convicted of felony duck theft.