Julie Jensen appeared to have it all: a husband, Mark, to whom she'd been married for 14 years, two sons and a nice home. In 1998 Mark told police he found Julie dead. Police called it a suicide, but D.A. Bob Jambois said, "It didn't look right." Mark was later convicted of murder, thanks partly to a letter Julie wrote foreshadowing it. <a href="http://abc.go.com/watch/2020/SH559026/VD55140544/2020-821-letters-from-the-grave-part-1">Watch the full story on "20/20" online here.</a>

Julie and Mark met while both were attending University of Wisconsin Parkside, in Kenosha, Wis.

Julie and Mark share a happy moment. Julie's letter was initially ruled to be inadmissible. After years of legal wrangling, the Wisconsin Supreme Court overturned this ruling, paving the way for a trial. Nine years after Julie's death, Mark was tried for first-degree murder. The prosecution's case took five weeks, the defense's five days.

"I would never take my life because of my kids — they are everything to me!" Julie wrote in her letter. She had filed for divorce years earlier but Julie's brother Paul testified that Mark told Julie she would never see their sons again if she went through with it.

Julie wrote in her letter that Mark had never forgiven her for a brief affair she had had years before. Mark had his own secrets. He was having an affair with a married co-worker. Ted Wojt told "20/20" Mark wanted Julie to be more sexually experimental, but she refused.

Julie, with one of her sons, weeks before her death. Dr. Richard Borman, Julie's long-time physician, testified that she came to see him days before her death and that he was worried. "She was highly upset. It was burned into my mind. I'd never seen her look like that. She was distraught, almost frantic, actually," he said.

Not long before her death, Julie gave an envelope to friends Ted and Margaret Wojt. She told them to give it to the police if anything happened to her. In the letter inside Julie said she feared Mark and disavowed suicide. She enclosed a photo of a list of Mark's she found referring to poison and syringes. <a href="http://abc.go.com/watch/2020/SH559026/VD55140544/2020-821-letters-from-the-grave-part-1">Click here to watch the full story on "20/20" online.</a>