The murder trial for a Colorado dentist accused of poisoning his wife to death has been put on hold after the defense attorney "suddenly quit" during jury selection.

James Toliver Craig, 45, is accused of killing his wife, Angela Craig, by putting poison in her protein shakes.

Angela Craig, a 43-year-old mother of six who was married to her husband for 23 years, died in March 2023 of poisoning from cyanide and tetrahydrozoline, the latter a substance found in over-the-counter eye drops, according to the coroner.

The trial has been delayed before and was set to begin Thursday with jury selection, KDVR reported. However, on Thursday morning, the defense counsel moved to withdraw from the case due to a "professional conflict," according to the 18th Judicial District Attorney’s Office. 

COLORADO DENTIST ACCUSED OF POISONING WIFE TRIED TO GET FELLOW INMATE TO PLANT FAKE SUICIDE NOTES: POLICE

The judge allowed the withdrawal under the Rule of Professional Conduct, and Craig declined to represent himself, delaying the case.

Craig allegedly flew his orthodontist lover from Austin to Denver while his wife was dying, according to a detailed arrest affidavit. The two also reportedly exchanged "sexually explicit emails."

The charging document described the couple's troubled marriage, financial difficulties and Craig's alleged sinister plot to murder her.

"In totality, this investigation has proven that James has gone to great lengths to try and end his wife's life," Aurora police Detective Bobbi Olson wrote in the affidavit. 

On Feb. 27, Craig created a secret email account, jimandwaffles.com, which he only used on a computer in his now-shuttered Summerbrook Dental Group, investigators said.

COLORADO DENTIST ACCUSED OF POISONING WIFE'S PROTEIN SHAKES TO START NEW LIFE WITH LOVER

Police say Craig searched online for things like "How to make murder look like a heart attack" and "How to make poison" days before his wife searched for symptoms she was having like vertigo, shaking and cold lips.

Craig also allegedly researched multiple "undetectable poisons" and purchased some, and he ordered a rush shipment of potassium cyanide even though it was not needed.

Investigators allege that Craig bought poisons online just before his wife began to experience symptoms that doctors could not find a cause for, but his lawyers have argued there is no direct evidence that he put poison in his wife’s shakes and have accused Olson of being biased against him.

Her sister, Toni Kofoed, told police that Craig had drugged his wife about five years earlier because he had planned to commit suicide and didn't want her to stop him.

Kofoed also told investigators that the couple's marriage had always been "tumultuous" and that Craig had "multiple affairs with several women" and had been "addicted to pornography since he was a teenager."

COLORADO DENTIST ACCUSED OF FATALLY POISONING WIFE ON VERGE OF FINANCIAL RUIN: COURT PAPERS

Angela Craig told her sister several times over the past 16 years that she planned to leave him, but he always convinced her to stay. The couple was also broke and on the verge of declaring bankruptcy for a second time, the documents allege.

Angela Craig had complained to her sister that her husband had recently gambled away more than $2,000 on a trip to Las Vegas.

Back in May, Craig was accused of asking a fellow jail inmate to plant letters in his garage and his truck to make it look like his wife was suicidal. Olson said the inmate believed the letters were written by Craig but were meant to appear as if his wife had written them.

According to Olson, Craig offered money to pay the inmate's bond in order to be released from jail or perform free dental work in exchange for planting the letters, but the inmate decided not to take him up on the offer and reported the incident to authorities, the detective previously testified.

Craig was already charged with first-degree murder and another count of solicitation to commit tampering with physical evidence. He pleaded not guilty to those two charges in Nov. 2023.

His next court appearance is scheduled for Dec. 16.

Fox News' Rebecca Rosenberg and the Associated Press contributed to this report.