A spokesman for Essex Police said:
"Evidence from fire scientists has indicated that the likely cause of the fire was malicious ignition.
"Detectives know that there was a burglary at the house on the same evening/early morning of the fire and are re-appealing for information and witnesses."
More top news
George Michael died in December last year at the age of 53.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.