Absolutely NOT!
This IS the work of a predator, period.. And NOT the MO of mink, weasel, or anything rodent. Sourland is likely correct. The other thing that enters coops AND removes head is raccoons, but it looks different not leaving the neck behind so cleanly like that, usually.
I've raised hundreds of "roosters".. THIS is NOT what damage cause by a rooster (or other hen) will look like.. NO game cam needed.. to verify it is NOT caused by YOUR flock. If a pullet, cockerel, or hen were found over the dead body and pecking it.. they were inspecting or happenstance suspects and not the original offenders.
At 5 months old.. and Orpington
cockerel is still going to be very immature and not have his full protective hormones on boards along with confidence that comes with age. You can cull if you like but it WON'T fix what happened.
Was it in the coop or under it.. do you have any photos? Possible it was two different incidences?? Or the inside coop one was attacked outside and took the blood in with her??
Please, verify.. did you lose 3 birds today? 3 losses in a single day is NOT *usual* for raptors in MY experience.. but I see and learn new things every day. Adding your location MAY help with more relevant suggestions... other possible predators.. domestic dog, fox, coyote, skunk, opossum, owl. etc.. yes, technically even rats if given the opportunity.
Very sorry for you loss!