Seven men have been arrested in connection with the deaths of the wife and children of Dublin-based neurosurgeon Muhammad Taufiq al-Sattar.
Shehnila Taufiq, 47, died along with her 19-year-old daughter Zainab and sons Bilal, 17, and Jamil, 15, in the suspected arson attack at the family home on Friday 13 September.
The arrests came after officers executed warrants at several properties in the Leicester area this morning.
The seven men, aged between 16 and 24, are in police custody while inquiries continue.
Kemo Anthony Porter, 18, has been charged with murdering the family and is due to appear at Leicester Crown Court at a later date.
Detective Superintendent Kate Meynell from the East Midlands Special Operations Unit said: "We appreciate that a number of residents may have been concerned with the police presence this morning, and we would like to thank the local community for their understanding and patience as officers carried out these warrants.
"This morning's activity was part of the ongoing investigation into the four deaths in Wood Hill earlier this month.
"We would also like to encourage anyone with information regarding the fire who has not already spoken to the police to contact us."