O'Sullivan's Gmail account was set up by Garda IT security experts
A private email account used by Garda Commissioner Nóirín O'Sullivan was set up internally by the force's IT department, the Irish Independent has learned.
The Garda chief is believed to have breached protocol by using an external account to access work-related materials over the past six years.
However, sources say the force's IT unit were fully aware of the situation and even set up the Google account for the commissioner.
At present, there are no plans to delete the Google account as it is used to update security settings on her official Android phone.
A source said that if Ms O'Sullivan deleted the account at the centre of the controversy, she would still be required to set up a new one.
Gardaí are satisfied that her Gmail was not hacked but the extent of the internal probe is likely to come under scrutiny when she appears before the Policing Authority tomorrow.
There is a concern that the Garda boss's Gmail username and password may have been among millions stolen in 2012 and placed for sale on the so-called 'dark web', which is frequented by criminals.
Garda HQ has said they have found no evidence that her account was compromised.
Cyber security expert Brian Honan, CEO of BH Consulting, told the Irish Independent that Google security settings can often be safer than defences put in place by company IT departments. However, he said the real level of protection comes down to the individual.
"There would be security concerns with all web-based email. The weak link is the user. How strong are their passwords and things like that," he said.
In a statement, An Garda Síochána said: "The Commissioner takes all recommended security measures when using Gmail, such as regularly changing the password, using a mix of letters, numbers and symbols for the password, and independent device authentication."
They added Ms O'Sullivan only used the Gmail "occasionally" in order to ensure Garda business was "discharged effectively".
Mr Honan said this is common in many workplaces where internal email systems are restrictive.
"It's something you see in companies quite often. People use personal accounts to be more productive," he said.
However, he added that there is a "million-dollar question" about who in Google can see the emails of users and what accounts they use.
While the company offers a free service, it does scan emails for keywords in order to sell targeted advertisements.
Meanwhile, Labour Party leader Brendan Howlin has said he would like to see more information about the type of emails the commissioner was accessing through Gmail.
"I'd like to see what was the content of those particular Gmails and how secure the secure systems are," he said.
The former minister said that while he was in government he "never believed any system was entirely secure".
"We need to see what particular emails were generated on a public system and how vulnerable that was," said Mr Howlin. He said ministers tended to have two emails accounts, one linked to the Oireachtas and another linked to their department.