Louis, 17, died after being stabbed in the chest in Northampton on Friday evening (May 25).
A 16-year-old boy and a 34-year-old woman from Northampton and a 37 year-old man from London were arrested on Tuesday night.
Detectives investigating the murder made a further arrest yesterday (Wednesday, May 30), arresting a 17-year-old boy from Northampton.
Catholic churches in Corby and Rothwell to close
Farmers and firefighters battled flames at huge field fire near Kettering
As firefighters battled a field fire near Kettering, two more were deliberately started
Who's been sentenced from Corby, Ecton, Higham Ferrers and Kettering
Burglars smash their way into Kettering home
Police are continuing to question all four of them this afternoon (Thursday).
The 16-year-old and 17-year-old were arrested on suspicion of murder.
The 34-year-old and 37-year-old were arrested on suspicion of assisting an offender.
Anyone who saw or heard anything suspicious in the Drayton Walk area of St David’s between 6pm and 7pm on Friday, May 25, or in or around Eastern Avenue North or the shopping parade in Newnham Road is asked to contact police on 101.
Anyone wishing to remain anonymous can call Crimestoppers, in confidence, on 0800 555111.