Ms O’Neill and other senior Sinn Féin members were among crowds who attended the funeral of Bobby Storey in west Belfast in June despite restrictions on public gatherings.
The scenes at the height of the pandemic sparked outrage and calls for the Deputy First Minister to resign.
A row with the DUP over the matter prompted the suspension of joint briefings with Sinn Féin during the health emergency.
It emerged on Friday that 14 people have been sent letters asking them to attend voluntary interviews at a local PSNI station.
A Sinn Féin spokesman confirmed on Saturday: “Michelle O’Neill and a number of the party’s elected representatives received letters from the police yesterday asking them to present for voluntary interview.
“They will contact the police and co-operate with the investigation.”
The police probe is being led by Cumbria Constabulary Deputy Chief Constable Mark Webster.
Earlier this month, Ms O’Neill acknowledged that Stormont’s public health messaging capacity had been undermined by the row over the funeral.
“It wasn’t my intention this would happen, but it did, I accept this and I regret this is the case,” she told RTÉ.
“I accept that we have not been able to deliver clear messaging in the format that was the practice before this controversy.”
Meanwhile a separate independent probe over access to the Roselawn Cemetery on the day of the funeral when eight other families were denied access due to pandemic measures is ongoing.
