Detectives in Dacorum investigating an arson in Northchurch after a woman returned home to find a blaze in her living room.
The fire was discovered at around 7.40pm on Monday, December 20 at the High Street home.
The fire service attended to deal with the blaze and make the area safe.
Damage was caused, but no one was injured.
It was established there were signs of a break in at the property, although nothing appeared to have been taken.
Detective Constable Karen Jordan, from the Dacorum Local Crime Unit said: “The occupant had left her home at around 2pm that afternoon, to exchange Christmas presents with family.
"Due to the signs of a break in, we believe the fire may have been started deliberately. This reckless behaviour could have cost someone their life.
“We’ve conducted extensive enquiries since the incident occurred, including speaking to people in the area and seeking any CCTV or forensic opportunities.
“We’re now asking the wider public if they can help. Were you in the area at the time and did you notice anything suspicious? If you have any information at all, please contact us.”
Alternatively, you can stay anonymous by contacting the independent charity Crimestoppers on 0800 555 111 or via their untraceable online form at crimestoppers-uk.org.