Police Scotland said the lost disc was found by an officer working within the force’s Counter Corruption Unit while “clearing their personal locker”.
The images had been seized to establish links between a serving officer and retired policemen as part of a probe into leaks coming from the investigation into the unsolved murder of sex worker Emma Caldwell.
The CCU began an internal investigation after stories appeared in the press about the investigation.
Last year the Interception of Communications Commissioner’s Office (IOCCO) said Police Scotland had been “reckless” in failing to obtain judicial approval when attempting to access communications data relating to the case.
Sir Stanley Burnton, the Interception of Communications Commissioner, said the force had sought communications data to determine a journalist’s source or the “communications of those suspected to have been acting as intermediaries between a journalist and a suspected source”.
A subsequent report by Her Majesty’s Inspectorate of Constabulary in Scotland (HMICS) found CCTV footage which formed part of the investigation connecting serving and retired officers had been lost.
But in a letter to the Scottish Parliament’s justice committee, Deputy Chief Constable Iain Livingstone said the missing disc had been recovered.
He said: “On 25 August 2016, an officer working within the CCU intelligence section was clearing their personal locker when they discovered the missing CCTV disc amongst the items within. The officer immediately informed their supervisors of the find.
“The content has been viewed by senior managers from the CCU who confirm it is the missing disc, which has now been formally lodged as a production in line with relevant Police Scotland procedures.”
Last month Police Scotland was ordered by the Investigatory Powers Tribunal (IPT) to pay £10,000 in damages to one of its former officers in relation to the case. The tribunal ruled the force had acted unlawfully when it obtained communications data.
Police Scotland has asked Durham Constabulary to carry out an independent inquiry into “matters arising from a breach of communications data protocols”.
Yesterday, the force said the circumstances surrounding the misplaced disc would form part of that inquiry.