Seven police officers have been served with 'Regulation 15 Notices' in relation to the investigation into the "Plebgate" incident.
The notices inform them a complaint has been made or a conduct matter has come to light involving them that warrants an investigation.
Three of those officers, a 52-year-old man, a 46-year-old man and a 46-year-old woman, have been arrested and bailed. All three remain suspended from duty.
A 23-year-old man, who is not a police officer or member of police staff, was also arrested and bailed in relation to the incident.
More top news
Liberal Democrat leader Tim Farron insists his party can be the "strong opposition that Britain desperately needs".
Sunderland have finally lost their battle against relegations and it was certainly years in the making, writes Simon O'Rourke.
Rain in the southwest of England will gradually spread further north and east.