A 22-year-old man has been arrested in Denmark on suspicion of murdering a Swedish national who was killed in front of his family on Christmas Eve.
Flamur Beqiri was gunned down in Battersea, south-west London, at around 9pm as he returned home with his wife and young child.
Detective Inspector Jamie Stevenson said the 36-year-old was shot multiple times in Battersea Church Road by a lone attacker who fled on foot.
The Metropolitan Police said a 22-year-old man was arrested at Copenhagen Airport in Denmark on January 20 on suspicion of Mr Beqiri's murder.
"He remains in custody in Denmark pending extradition proceedings back to the UK," a spokeswoman said.
Scotland Yard said Mr Beqiri, a Swedish national who had Albanian heritage, had been living in London for four or five years.
According to reports, he was the brother of former Real Housewives Of Cheshire star Misse Beqiri.
Shortly after the attack, Mr Stevenson said: "We believe Flamur may possibly have been involved in some criminality in Sweden, and are in liaison with our Swedish counterparts to try to understand what, if any, incidents there may have been that might have led to someone seeking retribution against Flamur in the UK."
According to reports, Mr Beqiri married his wife, Debora Krasniqi, in Cernobbio, by Lake Como in Italy, in October 2018.
An article in Grace Ormonde Wedding Style magazine, which published photos of the occasion, revealed that the couple met through Facebook.
Ms Krasniqi told the magazine that the pair, initially just friends, "fell deeply in love" at his sister's wedding after speaking for "endless hours over the phone".
"There was always something special about our connection and bond," she said.
In a statement released through Scotland Yard shortly after his death, Mr Beqiri's family said: "Our family are in a state of shock and are grieving. To have so much sadness at this time of the year is heartbreaking."
Neighbours living near the scene of the shooting described hearing multiple gunshots followed by a woman screaming "desperately" for help.
Vittoria Amati, 60, said she heard "eight to 10" gunshots fired in quick succession.
Mrs Amati told the PA news agency: "I then heard the screams of the wife. I came out and realised it was one of my neighbours.
"He was lying in front of his doorway in a pool of blood. He was still alive. We were really hoping he would make it.
"You have no idea how desperate she (his wife) sounded."