A 17-year-old boy has admitted setting fire to a motorway causing a major shutdown which left thousands of motorists stranded for many hours.
The teenager entered guilty pleas to two counts of arson reckless as to whether life is endangered on the M3 motorway on September 16 and 23.
The defendant, who cannot be named because of his age, was also accused of endangering motorists by placing a "flammable device" on the M3 on both occasions but he denied these two offences and his pleas were accepted by the prosecution.
He also pleaded guilty at Winchester Crown Court to eight charges of stealing computer equipment in burglaries at top public school Winchester College between August 2016 and June 2017 and blackmailing the headmaster.
The court has heard that he twice demanded payment of £10,000 in the online currency bitcoin from the school in order for him to stop carrying out burglaries.
Judge Keith Cutler ordered psychiatric reports to be prepared on the defendant who is being detained at a mental health hospital.
Adjourning the case for sentence on March 2 2018, the judge told the defendant: "There is a lot of work to be done by your legal team and the doctors and those treating you and they will be reporting back on your behalf. Please co-operate with them and tell them what is going on in your mind."
The M3 motorway, the main road between London and Southampton, was closed between junctions 9 and 11 at Winchester from just before 4am until after 3pm on September 23 causing gridlock throughout the area.
Social media users shared pictures of the scene with one showing a man walking his dog on the hard shoulder, others playing golf, and another doing a handstand on the carriageway.
Bomb disposal experts were called to the scene but police later said the substance placed on the motorway was flammable, not explosive.
In the earlier incident on the same bridge, police received reports of something being dropped on to the carriageway and that an object was alight, but when officers attended they found only broken glass and no fire.
An earlier hearing was told that the items were "incendiary devices" and the impact of the closure would have led to a cost of "millions of pounds".
The defendant, who appeared wearing a grey suit, white shirt but no tie, also pleaded guilty to two charges of theft of items from Tesco stores on the days preceding the two motorway incidents.