A new investigation is to start into whether mass murderer Harold Shipman killed patients when he worked as a junior doctor in West Yorkshire.
The investigation centres on Shipman's time as a junior doctor
The public inquiry into the former Hyde GP has received new information since his suicide in January.
A health professional who worked at Pontefract General Infirmary with Shipman has expressed concerns.
Dame Janet Smith, the inquiry chair, is to investigate Shipman's time at the hospital from 1970 to 1974.
The public inquiry being held at Manchester Town Hall has already looked at one death at the hospital during Shipman's time but decided he was not to blame.
The investigation will include looking at medical records and talking to families of those who died at the time.
A statement from the inquiry read, "Following Shipman's suicide in January 2004, a health professional who worked at Pontefract General Infirmary during the time that Shipman was employed there came forward to express concerns.
"In view of the nature of these concerns, the inquiry has felt it necessary to look again into Shipman's time as a hospital doctor in Pontefract.
"The process will involve examining any available documentary evidence, such as death certificates, cremation certificates and medical records, and talking to interested parties who may be able to provide relevant information.
"Contact with families will also be necessary."
A spokeswoman for the inquiry refused to elaborate on the concerns but said they would eventually be made public in a witness statement.
She added it was "too early" to say when the re-investigation would be complete.