Police in Northamptonshire have confirmed that Anxiang Du, the man suspected of the murder of a county family last year, is in custody.
It is understood the 53-year-old has been arrested in Morocco.
Spanish news agency EFE said the arrest had taken place, ending an international manhunt that started soon after the Ding family were killed at their home in Wootton, Northampton, in April 2011.
A police spokesman said: “Detectives hunting for Anxiang Du have been informed by Moroccan law enforcement authorities that a man they strongly believe to be the suspect has been arrested.
“The arrest happened on Saturday afternoon at a premises in Tangier - and authorities believe that the visit by Northamptonshire detectives to Madrid earlier in the week played a significant part in the suspect’s apprehension. Officers will now be progressing a formal application for extradition with the Home Office.”
Officers investigating the murders believe Anxiang Du fled to Morocco just days after the incident.
Helen Chui, Jifeng Ding and their daughters Xing and Alice were murdered on the day of the Royal Wedding last year at their home in Pioneer Close, Simpson Manor.
It has emerged that Du boarded a bus at London’s Victoria station shortly after the family were found dead and travelled to Paris and through France and Spain, before catching a ferry from the port of Algeciras to Tangier in Morocco.