James Toliver Craig was arrested for a ‘complex’ poisoning plot to murder his wife Angela (Pictures: Aurora Police Department / Facebook)

A Colorado dentist has been arrested after allegedly poisoning his wife with arsenic slipped into her morning protein shakes.

James Toliver Craig, a 45-year-old dentist with a practice in Aurora, was arrested on Sunday morning for what police called a ‘heinous, complex, and calculated murder’ of his wife Angela Craig, 43.

Angela, who was also the mother of his six children, was first admitted to Parker Adventist Hospital on March 6, complaining of abdominal pain, dehydration, vomiting, diarrhea, an altered mental state, and organ failure.

Just before she was admitted, James and Angela worked out in their home gym.

Family members called James and Angela Craig’s relationship ‘tumultuous’ (Picture: Facebook)

‘Before the workout, James made Angela a protein shake or pre-workout shake in which James gave her extra protein because she was feeling sluggish,’ an arrest warrant affidavit against James states. ‘After the workout, Angela became faint and dizzy, and ultimately James took Angela to the hospital.’

She was released the same day, but was hospitalized again at University Hospital Anschutz in Aurora on March 15.

Her condition worsened as she began suffer from severe seizures. She was eventually put on life support, but never regained brain activity and was pronounced brain dead later that day.

But James’s employees and business partners at his dental practice suspected foul play. An office manager at his practice opened a personal package addressed to James on March 13, and found it contained potassium cyanide.

Investigators were tipped off to Craig’s cyanide purchase by his business partner (Picture: Facebook)

Another employee noticed that James had been acting suspiciously in previous days. The employee noticed James using a computer for work in an unoccupied exam room, instead of his personal computer in his office.

When detectives searched the computer in the exam room, they found that James was using an alternate email address.

On February 27, James used the Google account associated with the secret email address to search for the phrases: ‘how many grams of pure arsenic will kill a human’ and ‘is arsenic detectable in autopsy?’

Using the same account, Craig then ordered 10 grams of arsenic off Amazon. The entire purchase cost $13.

James and Angela Craig lived in Aurora, Colorado with their six children (Picture: Facebook/SummerbrookDental)

According to the Centers for Disease Control (CDC), arsenic poisoning can cause ‘nausea, vomiting, and diarrhea to dehydration and shock’ in victims. The symptoms are very similar to what Angela experienced in her first hospitalization.

James also began searching for poisons on YouTube. His search history on the site included the videos: ‘Top 5 Undetectable Poisons That Show No Signs of Foul Play,’ ‘how to make poison,’ and ‘The Top 10 Deadliest Plants (They Can Kill You).’

After the initial arsenic orders, investigators found he then ordered potassium cyanide from a company called Midland Scientific.

After placing the order, a Midland Scientific employee followed up with him to ask about his need for the poison, and asked him to sign a Restricted Item Usage Statement before it could be shipped.

In the usage statement, James said he was a surgeon performing craniofacial reconstructions. He wanted to use the cyanide to help with the ‘layering of alternative metals.’ If the experiment was successful, he stated that he would be publishing the results with the National Institutes of Health.

This package of potassium cyanide was eventually delivered to him at his practice, but was opened by the office manager. When the employee questioned him about it, he ‘eventually recanted and admitted the package contained potassium cyanide, but claimed that Angela asked him to order it,’ his arrest warrant states.

James told investigators he thought his wife was severely depressed intentionally trying to overdose, but at least one investigator from Child Protective Services found this account suspicious.

‘None of Angela’s children mentioned their mother’s depression nor did they mention any alleged previous suicide attempts,’ the investigator said, and ‘believed that it was improbable that this type of event (overdose suicide attempt) could happen with no one inside the household, except James, being aware.’

Additional interviews with friends and family members revealed that the couple’s relationship had been ‘tumultuous’ for years.

‘James had multiple affairs with several women, told Angela he had been addicted to pornography since he was a teenager, and drugged Angela approximately five to six years ago,’ one person close to the family told investigators.

The same source told investigators that James refused to let the hospital conduct an autopsy on his wife after her death. ‘James said he felt if they couldn’t figure out what was wrong with her when she was alive he wouldn’t let them poke her more when she was dead.’

The affidavit also revealed that a search of James’s cell phone showed he was in a ‘sexually intimate relationship’ with an unidentified orthodontist from Texas. James allegedly flew his mistress out to Denver, Colorado while his wife was in the hospital.

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Police charged James Toliver Craig for the ‘heinous, complex, and calculated murder’ of his wife.