The thieves behind London's Hatton Garden jewellery heist tunnelled their way through a two metre concrete wall before raiding 72 security boxes, dramatic new pictures have revealed.
The images released today by police show how the gang entered the vault and the power tools they used to carry out the audacious £60 million Easter weekend raid.
The suspects used a heavy duty drill - a Hilti DD350 - to bore a hole 20inches deep, 10in high, and 18in wide to gain access to the vault.
When detectives arrived they discovered the vault covered in dust and debris and the floor strewn with discarded boxes, police said. Numerous power tools, including an angle grinder, concrete drills and crowbars had been left behind.
Police now believe the heist was executed over four days - between Thursday April 2 and Sunday April 5. Despite an alarm being triggered, the raid was discovered only when staff returned on Tuesday April 7 following the Bank Holiday break.
Officers believe the gang entered the building, which houses a number of businesses, through a communal entrance before disabling the lift so they could climb down the lift shaft to the basement.
After forcing open shutter doors, they bored holes into the vault wall to access the safety deposit boxes.
The Flying Squad have now completed their forensic examination of the scene, recovering around 400 items of evidence and thousands of hours of CCTV images.
Detective Superintendent Craig Turner, head of the Flying Squad, said the forensic work and inquiries had been "vital in order to ensure we are able to exploit all investigative opportunities to their fullest extent" and to help identify the thieves.
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"We appreciate that this situation has been frustrating for those affected by this crime and thank those individuals for their ongoing patience and support."
Scotland Yard said it is continuing to review why officers were not sent to investigate an intruder alarm set off at Hatton Garden Safe Deposit shortly after midnight on the Friday.
A call was received by the force's Computer Aided Despatch system from the security company but no police response was deemed necessary.
The failed response is now the subject of an internal investigation. Police will determine why "this grade was applied to the call in conjunction with the alarm company'.
A police statement said: "It is too early to say if the handling of the call would have had an impact on the outcome of the incident."
Of the 72 boxes opened during the burglary, officers have only been able to make contact with six people who are believed to be victims.
No arrests have yet to be made.