THE SNP has been criticised for failing to resolve its investigation into disgraced former minister Derek Mackay a year on from his resignation. 

Mr Mackay quit in February last year on the eve of the Scottish Budget after it was reported he had bombarded a 16-year-old boy with messages, including calling him "cute". 

The former finance secretary said he took "full responsibility" for his actions and had "behaved foolishly". 

READ MORE: Derek Mackay resigns as finance chief over inappropriate message scandal

However he has resisted calls to step down as an MSP before the election and continues to be entitled to his full £64,470 salary despite his absence from Holyrood.

He was also paid an automatic severance payment of £11,945 for loss of ministerial office and has continued to claim expenses.

Last year, First Minister Nicola Sturgeon said Mr Mackay had been suspended from the SNP pending an investigation.

But one year later, there is still no update regarding this probe. 

An investigation into former SNP children's minister Mark McDonald took less than four months to conclude he had sent “inappropriate and unwanted” messages to women.

Asked if the party's investigation into Mr Mackay is still ongoing, and if he is still suspended from the SNP, a party spokesman said there there was "no update on this at present".

Scottish Conservative MSP Graham Simpson said: "The SNP’s investigation into Mark McDonald only took a few months, quite a contrast to Derek Mackay’s probe which has been rumbling on for a year.

"The SNP have no excuse not to share their conclusions. Police Scotland’s own enquiries ended eleven months ago.

"We know how close Mr Mackay was to the Sturgeon-Murrell household. 

"It seems this is what counts when the SNP are deciding on the length and effectiveness of their internal processes.

"Any attempt to bury it because of the election and Mr Mackay standing down would be both cynical and wrong."

He said the SNP "must now come clean about what they have learnt from the investigation and any new procedures introduced as a result".

Mr Simpson also called on the Government to back his proposal for a "Mackay’s Law".

He said: "The legislation will stop MSPs benefiting from taxpayers’ money if they don’t do the job they have been elected to do and punish politicians who unofficially give up on their duties, like Mr Mackay.

"The pandemic has cost businesses dearly, with many livelihoods lost, and now more than ever we need set a clear example.  

"The SNP risks undermining public confidence in elected decision makers permanently if they fail to support Mackay’s Law.”

Scottish Labour interim leader Jackie Baillie said: "With millions of Scots facing a cost of living crisis, it is outrageous that the public is forced to pay Derek MacKay’s wages despite the fact he has not lifted his finger in the past year. 

"This gravy train has faced delays that even ScotRail would struggle to get away with.

"Rather than sitting on her hands, Nicola Sturgeon should kick Mackay out of the SNP, instruct him to resign his seat and allow voters the chance to elect someone who will actually do the job they are paid for.”

Mr Mackay is expected to stand down at the Holyrood election in May. He currently sits as an independent.

A spokesman for Mr Mackay said he is "focused on continuing to provide a constituency service as an Independent MSP, with more than 830 cases having been handled by his office on behalf of constituents during the last 12 months".