A 35-year-old man has been arrested on suspicion of conspiracy to commit arson after an explosion in Leicester killed five people.
The fire tore through a Polish supermarket and two-storey flat on February 25 on Hinckley Road.
Mary Ragoobeer, 46; her two sons Shane, 18, and 17-year-old Sean and Shane’s 18-year-old girlfriend Leah Beth Reek were killed in the blast, along with Viktorija Ljevleva, 22. Several others were injured.
The man was arrested on Wednesday, Leicestershire Police said.
Arkan Ali, 37; Hawkar Hassan, 32 and Aram Kurd, 33, denied manslaughter charges, separate counts of arson being reckless as to endanger life and fraud by false representation at a court hearing in April.
Ali, of Drake Close, Oldham, Hassan, of no fixed abode, and Kurd, of Hillary Place, Leicester, are set to appear at Leicester Crown Court on August 31.
The force said the latest suspect remains in police custody.
Emergency services responded to reports of the blast from concerned residents at about 7pm on February 25 and police declared a major incident.
Firefighters worked through the night to dig through rubble and tackle the explosion’s subsequent blaze.
Five other people were taken to hospital, one in a critical condition.