Found it:
Wallace had told police that he drove to the house after learning of the fire..
After delivering the ransom money on the morning of the fire,
police said, Wallace drove to Chantilly, Va., to help finish building a martial arts studio, and
authorities confirmed his location by tracking his cellphone and with receipts and surveillance video from a Virginia hardware store he visited.
Police said that Wallace received a call from someone at American Iron Works informing him that his boss’s house was on fire and that he immediately drove to Woodland Drive..
At 10:26 a.m.,
the police records show, Wallace texted Savopoulos, “Package delivered.”
Wallace then drove to Virginia. The fire was discovered about 1:15 p.m., and
police say Wallace was in Chantilly at the time.
http://www.washingtonpost.com/local...9031d4-0adf-11e5-a7ad-b430fc1d3f5c_story.html