ms. o'neill didn't smoke. >> i noticed there was white sand on the rear driver's side. we had a small amount of sand on the passenger side. >> in florida, sand is quite common. but not this kind of sand. >> it wasn't beach sand. it wasn't black mud. it wasn't coarse brown sand. it was unique. it was consistent with limestone. >> police dusted the entire car inside and out for fingerprints. >> we found over 20 prints in total. they were all over the car. they were on the inside. they were on the trunk. they were on the outside of the vehicle. >> on the day that denise went missing, her credit card revealed she bought a pair of women's sneakers at 2:30 in the afternoon, but failed to show up for work at 5:30. >> so somewhere in between that window something must have happened to her. >> this was one of the best pieces of evidence for the police because it gave them a time frame. >> no one at denise's apartment had seen or heard anything suspicious. but then a chilling call came in to 911. >> what is your emergency? >> apparently there is a body in the canal right by our h