A GP has appeared in court after being charged with attempted murder over an alleged poisoning.
Thomas Kwan, 52, is accused of trying to kill a man in his 70s, who was not his patient.
The Hong Kong-born doctor, of Ingleby Barwick, Teesside, was remanded in custody following his appearance at Newcastle Magistrates' Court on Wednesday morning.
Kwan did not enter any pleas, and was told he will next appear before Newcastle Crown Court on 6 March.
It is believed his medical practice is in Sunderland. A property in Ingleby Barwick has been searched by officers in protective suits in connection with Northumbria Police's investigation.
On Tuesday evening, a force spokesman said: "As part of an ongoing investigation, an address in the Ingleby Barwick area of Stockton was being searched.
"This led to the discovery of unknown substances and, as a precaution, officers are conducting further checks at the property.
"There is believed to be no wider risk to the public and inquiries are ongoing."
A spokesperson for Happy House Surgery, where Kwan is listed as a partner, said: "We are not able to comment as this is a police investigation.
"The practice remains open and our priority is to ensure continuity of care and services for our patients at this time."