The family of an MI6 worker from Anglesey whose body was found in a holdall at his central London flat say they are devastated by the discovery.
Gareth Williams, 30, from Holyhead, may have been murdered up to two weeks ago.
A communication officer at GCHQ in Cheltenham, Mr Williams had been been living in London after a secondment to the secret intelligence service.
His uncle, William Hughes said: "He would never talk about his work and the family knew not to ask, really."
Mr Williams was brought up on Anglesey, attending Bodedern secondary school.
A talented pupil, he had extra tuition at both primary and secondary school before studying at Cambridge University.
He went to St Catharine's College to undertake a postgraduate certificate in mathematics in 2000 but dropped out a year later.
His parents still live on the island. It is understood they have been taken by police to London after returning from holiday.
William Hughes, who is an Anglesey councillor, said he had had a phone call on Tuesday morning to say that Mr Williams' body had been found.
He said: "It was a terrible shock. I could not believe it, that such a thing had happened."
Mr Hughes said his "very talented" nephew did not talk about his employment.
He added: "He had worked for GCHQ for many years and I knew he was working in London doing something but he would never talk about his work and the family knew not to ask really.
"He was very talented in his work. He must have been. We don't know what he was doing. He never spoke about it."
The alarm was raised by Mr Williams' colleagues on Monday after they had not seen him for some time.
When officers broke into his flat on Monday afternoon, they found Mr Williams' body in a sports bag, as well as his mobile phone and several SIM cards.
The authorities are playing down any speculation that Mr Williams' death was linked to his line of work at MI6.
A post mortem examination was unable to provide a cause of death and further tests are to take place.
A Metropolitan Police statement said: "Officers from the Homicide and Serious Crime Command (HSCC) are investigating, and are treating this as a suspicious and unexplained death."
Anyone with information is asked to call the incident room in Hendon on 020 8358 0200 or, anonymously, the independent charity Crimestoppers on 0800 555 111.