Five servicemen are still being questioned about the death of a soldier during an exercise at an army barracks in Wiltshire.
Pte Williams died in Salisbury District Hospital
Private Gavin Williams, 22, of Hengoed, Caerphilly, collapsed at Lucknow Barracks, Tidworth, on Monday.
It is believed Pte Williams had been undertaking a disciplinary exercise for an act of misbehaviour.
Five men from his regiment, the 2nd Battalion The Royal Welsh, have been arrested on suspicion of manslaughter.
Ambulance crews were called to the scene and a spokeswoman for Wiltshire Ambulance Trust said that Pte Williams appeared "hot and agitated". He died later in Salisbury District Hospital.
The first four servicemen arrested - aged 44, 35, 31 and 28 - were taken to Salisbury Police Station for questioning.
They are due to appear before Chippenham magistrates on Wednesday as police seek permission to continue to detain them in custody.
The fifth man, aged 29, is also being held at Salisbury.
Wiltshire Police confirmed a Home Office pathologist had completed an initial post-mortem examination but that the cause of death remains undetermined pending further examination.
Police also renewed an appeal for information regarding the inquiry.
Geoff Gray, whose son - also named Geoff - died at Deepcut Barracks in Surrey, said that the "full force of the law should be brought to bear" against anyone found to be responsible for Pte Williams' death.
The Ministry of Defence said it was taking the incident "extremely seriously" but added that it was for Wiltshire Police to comment on the investigation.
On Wednesday afternoon Wiltshire Police were granted a further detention order for 36 hours over the four men who appeared at Chippenham Magistrates' Court earlier.