Updated 7.25pm, adds details
A 73-year-old man, Joe Bartolo known as il-Babakku, and his 56-year-old partner Carmen Abela, were killed at a garage in Marsa on Sunday morning.
The double murder took place at around 9.30am in Triq it-Tiġrija.
Police spokesperson Brandon Pisani said the couple, both Maltese nationals, were found dead at a farm.
The police said later that one suspect, a 34-year-old man from Ghana, was apprehended within minutes of the incident as he was seen leaving the site.
The police are also in possession of the murder weapon - a pair of pruning shears.
Sources said the property appears to have been used to host a number of migrants, including the alleged aggressor and another two people - a man and a woman from Nigeria, who helped the police catch the suspected culprit.
The couple had to be treated in hospital for some injuries.
A large number of police officers gathered at the scene of the crime soon after the murder. They included Keith Arnaud, who heads the murder squad.
An inquiry is being held. The police are investigating.