Martin McDonald, a former deputy sheriff and now a senior judge, said the remark was "facetious," The Louisville Courier-Journal reported. McDonald told David Barron, an assistant public advocate, never to call him again unless the opposing counsel was involved.
Barron, who represents Roger Dale Epperson, who was sentenced to death for two killings in the 1980s, said he made the call to the judge about a scheduling problem with the permission of the opposing lawyer.
McDonald made the threat during a videotaped hearing Friday, the Courier-Journal said.
"If you ever call me on my cellphone again, I'll strangle you," the judge said on tape, adding a threat to get Barron's law license "yanked" if he called without the opposing lawyer.
McDonald has a history of controversies. He was removed from a civil case in mid-September for bias.
He also once described a murder defendant as an "animal," said jurors "kind of missed it" when they returned a verdict of manslaughter instead of murder and sanctioned a juror who produced two doctors' notes to show he was sick.
McDonald, 54, has formally retired but remains on senior status. In Kentucky, that allows judges to serve for an additional period of up to 600 days to increase their pensions.