Five cabinet ministers, all from the Calgary region, have been interviewed by the RCMP as part of its ongoing investigation into allegations of voter fraud in the 2017 United Conservative Party leadership race.

Justice Minister Doug Schweitzer and Infrastructure Minister Prasad Panda previously confirmed their police interviews.

CBC News has now confirmed that Culture Minister Leela Aheer, Seniors and Housing Minister Josephine Pon and Associate Minister of Mental Health and Addictions Jason Luan have all been interviewed as well.

Through press secretaries, all three ministers say they spoke with investigators and that they are not under investigation.

Peter Singh

In addition to the cabinet ministers, at least one UCP MLA has also been interviewed by the federal police force.

Just before the provincial election, RCMP raided Calgary-East MLA Peter Singh's business as part of the voter fraud investigation.

Singh also faces allegations of "fraud, forgery, improper inducement and bribery" in his effort to secure the UCP nomination in his riding. That investigation is being carried out by Alberta's election commissioner.

A spokesperson for Premier Jason Kenney says he has not been interviewed.

The investigation

The investigation is focused on whether voter fraud took place in the 2017 UCP leadership vote that elected now-Premier Kenney.

The Alberta Crown Prosecution Service has appointed an out-of-province prosecutor to provide advice on the investigation.

CBC News has confirmed that fraudulent email addresses, all connected to a single source, were used to cast ballots in that vote.

The UCP has consistently defended the process and said audits had turned up no indications of wrongdoing.

Former UCP MLA Prab Gill has alleged in a letter to the RCMP that the Kenney leadership campaign used fraudulent emails to intercept personal identification numbers needed to cast a ballot in the leadership race. Gill said those PINs, which should have been sent to individual members, were then used by the Kenney campaign to vote for Kenney.

CBC News has not independently verified Gill's claims.

'Can't get any more serious'

Mount Royal University political scientist Duane Bratt says it's significant that the RCMP appears to be conducting a "pretty thorough investigation."

"The two major things is the deliberateness that the RCMP is pursuing this with and the second is the seriousness of this," he said.

"It's about whether the election was stolen. So that's as significant as you can have. You're talking about the leadership race of the current premier — that can't get any more serious."

Bratt says he is curious if the RCMP has interviewed Premier Kenney or those close to him and anticipates if it hasn't already happened, it will come late in the investigation.

'Kamikaze' campaign

In addition to the voter fraud investigation, Alberta's election commissioner has been probing the financing of Jeff Callaway's "kamikaze" campaign.

Callaway ran for the purpose of attacking Kenney's chief rival, Brian Jean, before stepping down and endorsing Kenney

Both men deny the allegations, but CBC News has obtained emails showing higher-ups in Kenney's campaign circle providing resources — strategic political direction, media and debate talking points, speeches, videos and attack advertisements — to the Callaway campaign.

There was a timeline for when Callaway would drop out of the campaign and throw his support behind Kenney.

Kenney's deputy chief of staff, Matt Wolf, even emailed a resignation speech to Callaway the day he dropped out of the leadership race.

So far, $77,250 in fines have been levied in that investigation. The majority of the fines were for donating to the campaign with money that was not their own.

It's alleged money was funnelled into the campaign from a corporation and distributed by Callaway's former communications director, Cameron Davies.