BBC Newsline investigates deer carting issue
The animal lay silently in the darkness of the trailer, its eyes burning red in the viewfinder of the men's night-vision camera.
It seemed unperturbed by their presence, familiar with human attention.
The two men knew the farm complex well. They had been here many times. They knew that deer were kept here in pens, fed, watered, cared for.
They finished filming the animal, almost silently closed the trailer's hatch, and slipped away into the night. They would see this animal again - soon.
For some time, the USPCA had believed deer from the farm complex, near Hillsborough, were being 'carted' to be used in hunts. 'Carting' is when captive animals are moved by trailer to a location then released to be hunted.
When BBC Newsline learned that a hunt was to be held last Thursday, the charity decided to mount a surveillance operation at the farm. On Wednesday evening, they watched as a deer was loaded into a trailer.
On Thursday morning, they followed the trailer to a location close to Katesbridge. Nearby, the County Down hunt was saddling up and moving out.
All day, the animal remained in the trailer. People approached it, but it was not released. That night, it was moved into a shed at the same location.
There it remained for four days
On Tuesday, once again, BBC Newsline had learned a hunt was to take place, once again it was to be in the Katesbridge area.
The USPCA were still watching the deer. Around half a mile away, the hunt began to assemble.
As the time for the riders to set off drew nearer, the activity intensified around the deer's shed. A fence was erected to guide the animal out and a mounted rider wearing hunt livery circled nearby.
Almost simultaneously with the hunt setting off, the deer was finally released. The lone rider pursued it up a nearby hill. Within six minutes, the rest of the hunt came galloping past the shed before following the deer's trail up the hill.
Throughout the afternoon, we followed the hunt. Often, we found ourselves among its followers and supporters.
At times, I could have reached out to touch the horses. But we couldn't film anything without risking giving away our presence.
As afternoon began to slide towards evening, it was clear the hunt was winding down. It appeared the deer had got away. I decided to approach some of those taking part.
Most of the riders wore black jackets, three wore red. I had been told these were the people I needed to speak to, the masters.
The first rider decided not to speak to me but, instead, to urge his walking horse into a gentle trot - away from me.
The second huntsman was willing to talk. He insisted they only ever hunted "outliers", a common term in hunting circles for deer living in the wild.
I told him what we had witnessed, but he again insisted they only ever hunted "outliers".
So, had we witnessed a criminal act?
Well, the USPCA believes we had, the department of agriculture suspects we had, the courts have yet to decide.
The law says it is an offence to hunt a protected animal. It also says any animal under the control of man, permanently or temporarily, is a protected animal.
This deer was clearly under the control of man, and so a protected animal, up until the point of its release. The legal question though is whether or not that status still applied after its release.
The legislation involved is the Welfare of Animals Act (NI) which was updated in 2011.
So far, that act has not been tested in court in relation to 'carting'.