A man has been questioned in Germany over the murder of a British computer games enthusiast he allegedly met on the internet, police said.
He is accused of flying to the UK to murder 20-year-old Matthew Pyke, stabbing him several times at his flat in Nottingham city centre.
Mr Pyke, who ran his own online chat forum dedicated to gaming, was found last Friday evening. It is understood his girlfriend Joanna Witton discovered his body.
Police in both Germany and Nottinghamshire have said Mr Pyke met his alleged killer on the internet.
Nottinghamshire Police, fearing Mr Pyke's attacker could strike again, tracked Heiss down through a series of postings on the internet, before asking colleagues in Germany to arrest him on Wednesday night.
Mr Pyke, who used the virtual online alias Shade, ran a website dedicated to the Nintendo game Advanced Wars in which gamers could chat with one another about tactics, characters and plots.
According to some reports, the arrested man and Mr Pyke had an argument on the website shortly before the alleged murder.
Mr Pyke, originally from Stowmarket, Suffolk, was about to start a degree course at Nottingham Trent University.
In a statement released through Nottinghamshire Police, German police said: "Limburg-Weilburg police have arrested a 21-year-old man from the rural district of Limburg.
"He was arrested by officers from the West-Hessen police headquarters in Hunfelden on suspicion that on 19 September he killed a man in Nottingham with a knife. They got to know each other through the internet."
The statement added: "The man has been extensively interviewed by Limburg CID at the petition of the public prosecutor in Limburg.
"He was brought before the Limburg judge who gave an order of detention with a view to extradition.
"Co-operation between police at headquarters and Nottinghamshire Police was very smooth and most successful. The joint investigation is still on-going and will be referred to Nottinghamshire Police."