Detectives investigating the murder of Little Gaddesden pensioner Graham Buck have taken three more people into custody in connection with their inquiries.
The Little Gaddesden pensioner died from stab wounds following an incident at near his village home on Saturday afternoon.
Ian John McLoughlin, 55, was arrested in Tottenham, North London in the early hours of Wednesday morning on suspicion of murder and robbery.
The arrests were carried out by Metropolitan Police officers acting on behalf of the Herts force.
Investigators now say that three further people were also arrested in Tottenham on suspicion of assisting an offender.
Although no names have been released, they are described as a 54-year-old woman from Tottenham, a 50-year-old man from Hackney and a 45-year-old woman from Edmonton.
All four people remain in custody at Hatfield police station as the investigation continues.