Police have released a CCTV image of a man they want to trace over suspected arson attacks on two homes.
Two properties in Kingston Road and Plantation Road in the Jericho area of Oxford had burning material posted through their letterboxes at about 02:45 BST on Monday.
Two people were taken to hospital with severe burns but have been discharged.
A man was arrested on Wednesday on suspicion of arson with intent to endanger life.
The 30-year-old from Stratford-on-Avon has since been released on bail.
Det Insp James Mather, of Thames Valley Police, said: "We are releasing a CCTV image of another man officers would like to speak to in connection with our ongoing investigation into these arson attacks in Jericho.
"If you recognise or have information about the man in the image, please contact us."
He has also appealed for any footage people might have that could help.
The force said there was an increased police presence in the area.