Former SNP leader Gordon Wilson has said Police Scotland has “fallen apart” and needs a radical overhaul to restore public trust.
The single Scottish force has been dogged by controversy since its formation in 2013.
Policies such as the routine arming of police and use of stop-and-search have been widely condemned.
Pressure on chief constable Sir Stephen House has mounted since police failed to response to an emergency call about a crash on the M9 in July in which two people died.
It emerged on Tuesday that one of the victims, Lamara Bell, was alive and trying to escape the wreckage when rescuers finally arrived on the scene after a second call 72 hours later.
Now Mr Wilson has launched a discussion paper through the Options for Scotland think-tank.
He said Police Scotland needs de-centralised, with four regional forces created, and local authorities given more oversight.
And the former Dundee MP has also launched a stinging attack on the SNP Scottish Government, saying MSPs, ministers and civil servants must “accept responsibility” for the failings of Police Scotland.
He said: “Rarely in the history of police forces has everything fallen apart as in the case of Police Scotland.
“The problems cannot be resolved by cosmetic actions such as a change in Chief Constable and calls for the resignation of the current Chief Sir Stephen House are puerile and nothing more than shallow political posturing.
“Real thought is needed and this is why I am launching an Options paper setting out substantial ideas for change in the hope that it will stir debate.
He added: “The problem goes much deeper than Sir Stephen House. Here the Parliament, ministers and civil servants must accept responsibility for the framework and legislation.
“To ‘retire’ Sir Stephen in a cosmetic move will do nothing to tackle the real difficulties of Police Scotland.
“These stem from over-centralisation. When creating a single national force, no account was paid to the reality that although Scotland is a small country, it nevertheless is a varied one. Different policing practices had been devised over the years to suit local conditions.”
Mr Wilson added: “What will not serve is an attempt to paper over the cracks by merely appointing a new Chief Constable or Chair of the Scottish Police Authority while failing to address the depth of the problems stemming from over-centralisation. It is time for ‘root and branch’ reform.”
His recommendations include decentralising the force by establishers four regional forces, each of which will have its own chief constable, giving councils joint oversight, scrapping the Scottish Police Authority and transferring national oversight tot he Scottish Parliament’s justice committee.