A "highly professional soldier" is believed to be responsible for a £1 million series of armed raids on prosperous homes in the Home Counties.
Detectives say that the meticulous research and use of extreme violence by the lone raider suggest the thief, who raids homes while armed with a sawn-off shotgun, is currently or has previously served with the armed forces.
The burglar is believed to stake out his targets for several weeks in order to intimately understand the comings and goings of the wealthy occupants and learn the locations of safes and valuables inside.
The "well-spoken intelligent thief" is also believed to have entered some of the properties prior to the raids in order to better understand the layout of the rooms.
In one raid, he was so confident that the alarm could not be raised that he spent more than an hour with the occupants until he had gathered all the items he wished to steal.
Detective Inspector Dee Fielding, from Surrey Police, said the use of cable ties, the level of planning and his confidence in carrying out such raids alone suggested he had a forces background.
She said: "Each of these burglaries have been extremely distressing for the victims involved.
"We do not believe this to be the work of an opportunist burglar, but someone who has specialist knowledge and skills - possibly ex forces or from a similar background due to the way he has behaved and the circumstances of each incident.
"The burglaries all appear to be the work of someone who knows exactly what they are doing and who is incredibly decisive in their actions.
"On each occasion unnecessary levels of violence has been used in addition to a firearm, which he used to threaten the victims, who have then been tied up.
"He has worked quickly and appears to have knowledge of who is home at the time of each attack, the location of safes and the layout of the home.
"This leads us to believe he has planned the attacks in advance with a great level of detail and prior knowledge.
"More than £1 million worth of valuable items, including irreplaceable heirlooms, have been taken on each occasion."
Ms Fielding said that DNA evidence had been found at the scene of one of the raids but this had not been traced to any other offences.
She added that the raids have occurred about once every six months, possibly as the offender needed more money.
In a three-year period between November 2014 and October 2017, the thief, who has left little forensic evidence, has carried out seven raids - two in Kingswood, Surrey, and others in Maidenhead, Berkshire; Chichester, West Sussex, Sevenoaks, Kent; Maidstone, Kent, and Virginia Water, Surrey.
Victim Susan Morris, 61, whose home in Kingswood, Surrey, was raided in October 2017, described the violence used, saying: "One point when he was hitting me with the gun pointing at me, at that moment I did actually think, 'this is it, it's all over'."