Detectives investigating the suspicious deaths of hundreds of patients at the Gosport War Memorial Hospital in the 1980s and 90s have been carrying out searches at the hospital.
A police investigation is underway to establish if criminal charges should be brought.
Records examined by the Gosport Independent Panel showed 456 patients had their lives shortened between 1989 and 2000 through the medically unjustified administration of opioids.
An investigation in 2018 found that the "institutionalised regime" of prescribing the drugs without medical justification "followed a clear pattern over time", and continued despite concerns being raised by nurses between 1991 and 1992.
But the report adds at least another 200 patients "probably" also had their lives cut short, when missing records are taken into account.
The searches, which took place on Sunday, are being kept deliberately low key to disrupt patients and the hospital as little as possible.
It is understood they are looking for 'outstanding documents' not seen by the previous inquiries.
And there have been four of those, plus three police investigations and another half a dozen reports, none of which have instilled confidence in many of the families.
Gillian MacKenzie, who is the daughter of Gladys Richards, was the first to alert police after the death of her mother, saying only a public inquiry and a trial will bring peace of mind.
The investigation itself is expected to last another three years, with its conclusions keenly anticipated by the victims' families.