Sounds very much like you have a male there, who is only interested in mating, since he's warmed up this season. I would imagine he kills the first mouse out of instinct, but has no interest in eating because he wants a female.

If he ignores any of the live mice, please make sure you take them out of his cage. I just recently rescued two snakes from a guy who thought he should just leave them in there. The snakes are still healing from their rodent bites. I only feed frozen/thawed, so no risk of that now. ^_^

I would say your snake should be acting "normal" again in a month or so.
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Holly

0.1 Lavender California Kingsnake (Lizzie Borden) (missing )
1.0 Florida Kingsnake (Eddie Gein)
0.0.2 Cornsnakes (Lyle & Erik Menendez)
1.0 Bearded Dragon (Charley Manson)
1.0 Orange Marmalade Cat (Oliver)
1.0 Black Cat (Shadowfax)
1.0 Egyptian Arabian (Bagan) (Deceased )
1.0 Tennessee Walking Horse (Durango)

2.0 Toddlers (Justice & Trevor)