The details: McMillan, of Peterhouse Close, Ipswich, faced charges of murder and being concerned in the supply of cannabis when he appeared before magistrates today.
The case was subsequently referred to Ipswich Crown Court, where McMillan was remanded to next appear on 20 October.
For context: Officers discovered 63-year-old McNicholl, known as Billy, dead at his Hawthorn Drive home shortly before 18:00 on 1 January. A Home Office post-mortem examination determined he died from head injuries and a stab wound to the right shoulder.
McMillan was first arrested on 22 January when he was 17, before being bailed with conditions. He was re-arrested on Monday and charged following questioning at Martlesham Police Investigation Centre.
The bigger picture: The Major Investigation Team's inquiry has resulted in five arrests total. Three other suspects arrested on 1 April remain bailed to return on 1 October, whilst a woman in her 50s has been told she faces no further action.
What's next: McMillan will remain in custody until his crown court appearance in October, where the case will progress towards trial.
