The investigation continues in the murder of four people found dead inside a multimillion dollar Northwest D.C. home last week.
It was the fifth straight day investigators sifted through the home on Woodland Drive looking for clues as to who killed Savvas Savopoulos, his wife, Amy, their 10-year-old son and their housekeeper, Veralicia Figueroa.
At the home, investigators paid close attention to the surveillance cameras that face the exterior. However, according to a police source, there is no video from the home that would point to the person responsible.
"Whenever we have any of these very tragic incidents, one of the first things we point to is mental illness," said Jay Singh, a forensic researcher and president and CEO of the Global Institute of Forensic Research.
He said there are five types of arsonists and they may be:
1. Suffering from mental illness
2. Experiencing a state of excitation
3. Looking to file a false insurance claim
4. Seeking revenge
5. Trying to conceal a crime scene
"It seems, at least in this case, that either revenge or concealment would be the most likely subtypes," he said. "It seems to be here though the individual has insight into what they were doing, was thinking relatively clearly and that it could be certainly, because there were no signs of forced entry, that this was someone who was either known to the family or had some way of being able to gain access to the home."
FOX 5 obtained audio from the first responders on the scene.
"Rescue … (unintelligible) ... three victims removed second floor … (unintelligible) … I'll need medic units," a first responder said.
"Also, if you would advise the chief, the room (unintelligible) is a crime scene."
Police sources tell FOX 5 the fire started in a room on the second floor where 10-year-old Phillip Savopoulos was alone and away from his parents and their housekeeper.
"The child can become almost a bargaining chip, which is a terrible way to think about it," said Singh. "But in a situation like this, certainly to be able to get information or resources -- it could be financial or non-financial -- from the adults in the family, then it's something where the child could be used almost as leverage."
Figueroa's step daughter told FOX 5's Paul Wagner that Figueroa's husband came to the Savopoulos' home on the morning of the fire looking for his wife because she had never made it home. No one answered the door. He left and then received a phone call from Savvas Savopoulos saying his wife, Amy, and Veralicia Figueroa had gone to the hospital.