Police investigations into the death of an Otago remand prisoner have been stepped up following the involvement of New Zealand's police watchdog in the case.
The Independent Police Conduct Authority (IPCA) received a complaint from Wellington drug and alcohol counsellor Roger Brooking in March regarding patient medical treatment at Otago Corrections Facility.
Mr Brooking laid the complaint after he found out police had done "absolutely nothing'' in investigating the February 2011 death of Jai Davis.
At the same time, Mr Brooking also raised concerns with the IPCA about the police investigation into the October 2010 suicide of Otago prisoner Richard Barriball.
One month after Mr Brooking laid his complaint, police dedicated a full-time team to Davis' investigation.
"Basically, he died two years ago and police had done absolutely nothing,'' Mr Brooking said.
Families of both men, who were considered at-risk prisoners, were concerned about what was happening.
"I think it's been very hard for them,'' he said.
The IPCA today said it was reviewing the investigations into the deaths deaths.
"The authority has asked police to consider any issues raised about Mr Barriball's death during their investigation of Mr Davis' death,'' it said.
Police said officers had been investigating Davis' death on behalf of the coroner since it occurred.
"The investigation has been complex and has developed as new information has come to hand.''
A full-time team has been working on the investigation since April, police said.
"With regard to Richard Barriball, we confirm that we have been reviewing the investigation file in relation to his death.
"These are both current investigation and police are not able to comment further until they are completed.''