Colorado dentist to enter a plea in fatal poisoning of wife, mother of 6

A Colorado dentist is set to enter a plea Tuesday to a first-degree murder charge for allegedly poisoning his wife and the mother of his six children so he could start a new life with his mistress.

Investigators accused James Craig, 45, of spiking protein shakes for his wife, Angela Craig, with cyanide and arsenic before her March 18 death.

His wife of 23 years died of poisoning from cyanide and tetrahydrozoline, which is found in over-the-counter eye drops, according to the coroner. 

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

However, testing did not find traces of cyanide or arsenic in the bottles used for her post-workout protein shakes, it was revealed at a July hearing. 

Investigators have not publicly disclosed how they believe he administered the tetrahydrozoline.

COLORADO DENTIST ACCUSED OF FATALLY POISONING WIFE TO BE WITH LOVER FACES HIS KIDS IN COURT

Before his wife's death, Craig had searched online "is arsenic detectable in an autopsy" and "how to make murder look like a heart attack," according to an arrest affidavit. 

In the following days, Angela Craig, 43, Googled the symptoms she began to suffer, including vertigo, shaking and cold lips, according to prosecutors. 

As she languished in the hospital with doctors unable to figure out what was wrong with her, Craig was meeting his mistress, orthodontist Karin Cain, prosecutors allege.

Cain, of Austin, Texas, told ABC's "Good Morning America" that Craig had told her he was in the midst of a divorce and no longer lived with his wife, which was not true.

On Angela Craig's third stint in the hospital in two weeks, she suffered a seizure March 15 and was declared brain-dead. She was removed from life support three days later.

The investigation into Craig began after his business partner and friend, Ryan Redfearn, told police that a package of potassium cyanide was delivered to their dental practice in Aurora, Colorado. There was no medical need for the drug. 

Detectives soon found Craig had placed several orders for various poisons, including arsenic and oleandrin. Craig is being held in jail on a $10 million bond.

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After his arrest, he was charged with tampering with evidence, but authorities have not disclosed the basis for the allegation.

Craig was deeply in debt and on the verge of bankruptcy when he hatched the alleged murder plot.

The Associated Press contributed to this report.