A woman has been arrested on suspicion of neglect and fraud as part of a police investigation into the deaths of 12 people living in care homes run by the same company.
Currently Sussex Police is looking at how residents at nine out of 20 care homes run by Sussex Health Care (SHC) were treated, while West Sussex County Council has stopped placing people at some of the homes run by the firm.
The woman was arrested on Thursday morning and remains in police custody.
Sussex Police have not released any further information on the woman, only confirming that she is from West Sussex.
Earlier in November, social services staff removed four people from Orchard Lodge, in Warnham near Horsham, which is one of the sites under investigation.
A spokesperson for the council said the removal of people from the home came following a "further risk assessment" and after the Care Quality Commission (CQC) placed the home in special measures when it was given an inadequate rating in September.
During the unannounced inspection in July, the CQC's report said the safety and leadership at the home was inadequate and the effectiveness and quality of care requires improvement but staff were good at responding to the needs of residents.
The council spokesperson continued that it will continue to "look in detail" at services run by SHC, adding: "Our priority has always been, and will remain, the safety and care of people living in care homes."
SHC said it would continue to work "openly with the police and county council" during the investigation.
A spokesperson for the coompany added: "We are seriously concerned about the impact the ongoing speculation is having on our residents, relatives and staff.
"We firmly believe that, as an organisation, our care practices and training are of a high standard, and that we continue to provide quality care on a daily basis."
Former West Sussex County Council's deputy leader Peter Catchpole, a paid adviser for SHC, left his post as cabinet member for adult social care so there was "no risk of conflict" between his role and his work for the company which he had declared.
He later stood down as deputy leader for "personal reasons", a statement issued by the council said.
Charity Compassion In Care set up a whistleblowers' hotline in the wake of the investigation.