Culpepper and another former Knight attorney, Matthew Fletcher, were arrested last week and released after spending a night in jail. No charges have been filed against them in court.
Culpepper said he never did anything wrong, was improperly arrested and doesn't expect charges to be filed.
"What they were charging me with is impossible," Culpepper said outside court. "I'm charged with defending my client as to this murder and they're charging me with accessory to murder after the fact based on a false confidential informant sham kind of program."
Culpepper, who represents Knight in an unrelated robbery case, said he was never told why he was arrested or what murder the charge referred to.
Prosecutors filed papers in court last year that said Culpepper had contacted a sheriff's department informant and agreed to pay him to testify that he was present at the time of the crime and witnessed events that would help Knight's case.
Those same court papers accused Fletcher and Knight last year of tampering with witnesses. Transcripts of recorded conversations suggested they discussed fabricating testimony and Knight tried to pay off witnesses with his lawyer's help.
Fletcher denied suggestions he was talking about bribing witnesses.
Although Culpepper hasn't been charged with any crime, Knight had to acknowledge he was aware of a possible a conflict of interest if the attorney was investigated or prosecuted by the same authorities. Judge Ronald Coen said Knight would not be able to later raise that issue on appeal after waiving that right.
Knight referred to the jailhouse recordings and said it wasn't true they tried to pay witnesses.
"I'm not Donald Trump, but it's fake news," Knight said.