. >> at the autopsy the medical examiner discovered petechial hemorrhages in helena's eyes, an indication of strangulation. there were no signs of sexual assault. but under helena's fingernails were tiny traces of what appeared to be blood. unfortunately, the sample was too small for forensic analysis. >> what comes to mind when there's a bizarre murder, strangulation in broad daylight? you think marital trouble. you think crime. you think drugs. i mean, helena never got within a thousand miles of any of those things. and that simply deepened the mystery. >> helena's husband, roger, was the first person police interviewed. >> whenever a woman is killed the prime suspect is generally the husband. and statistically, that bears out. most women who are killed are killed by someone well known to them, usually a romantic interest. and the husband is often the perpetrator. >> roger said he left home at 8:00 a.m. and was at work at the time of his wife's murder, around 9:00 a.m. records indicated helena had been on the telephone until 9:00 a.m., about the time a neighbor heard a commotion. >> one

. >> but he did find small, broken blood vessels in the whites of jenna's eyes, known as petechial hemorrhages. >> they're in that constellation of findings that we refer to as stigmata of asphyxiation. tells me i need to look for a cause of asphyxiation. >> and he found it. jenna's larynx had been crushed. the conclusion was inescapable. >> this is a strangulation, and in great probability, manual strangulation by hands. >> a background check revealed that over the years, spencer and jenna had broken up several times, dated others, but always made up and got back together. >> knowing there were no signs of forced entry, i think you meet think, this was some kind of lovers' quarrel gone bad. >> we did ask spencer if he had killed jenna, and his response was "absolutely no." >> but would the forensic evidence support his claim? >>> as investigators looked into jenna verhaalen's background, they learned she was well liked and respected by her friends and classmates at blinn college in texas. >> she didn't have any enemies, she didn't have fights with people, she didn't have arguments or disagree