A garage is being searched over a suspected poisoning after "unknown substances" were found in a house.
Doctor Thomas Kwan was charged with attempted murder in Ingleby Barwick, near Stockton-on-Tees, on Tuesday. The alleged offence happened in Newcastle.
A woman in her 30s was arrested on suspicion of attempted murder and was bailed pending further inquiries.
Cleveland Police said it wanted to reassure residents there was no risk to the community's safety.
Detectives said there would be an increased police presence in the area of Brading Court, in Ingleby Barwick, in the next few days.