Do you hear the dogs barking? -- Conan Doyle
Certainly from what I remember reading more than one perpetrator almost certainly was involved.
From #31 link:
"...The man appears to be a former tenant of the family's home. According to out source the possible suspect was picked up this morning on Charles Street and is now being interrogated by the FBI, and he is giving them valuable information on the crime. But he claims he is not the killer..."
What's Charles Street like? Seedy? Early report, but not detained at home or work apparently.