Burglars ransacked a caravan and stole a widescreen television before pouring petrol over the owner's property.
The caravan, off Scalby Road, Southminster, was targeted between 2.30pm on Thursday and 7am on Friday.
PC Leanne Smith said: "This crime would have been visible to anyone who was walking past.
"People carrying widescreen TVs down the street at odd times of the evening, night or early morning are usually considered suspicious.
"We would ask people who either of these two events to tall us, including those people who may have been offered a widescreen TV for sale in unusual in the past few days.”
A forensic examination of the property was carried out.
Call Chelmsford police on 101 or Crimestoppers anonymously on 0800 555111.