(CNN) -- Julie Jensen's words from the grave provided the key evidence that convinced jurors her husband was guilty of murdering her with poison, they said.
Julie Jensen wrote this letter and gave it to a neighbor before she died in 1998.
The handwritten letter detailing evidence and suspicions about Mark Jensen was the critical factor in the trial that ended in Wisconsin on Thursday, almost 10 years after Julie Jensen died, members of the jury said.
"She left a road map to her murder," juror Sandra Schott said. "And her murderer."
Jensen, 48, was found guilty of his wife's murder after more than 30 hours of deliberations. He faces a mandatory sentence of life in prison, but whether he is eligible for parole will be decided at his sentencing, scheduled for Wednesday.
Prosecutors contended that Mark Jensen poisoned his wife, then 40, with antifreeze and then suffocated her in 1998, but the defense argued that Julie Jensen was a depressed woman who killed herself and framed her husband.
Julie Jensen investigated her husband, checking his planner, photographing a note and documenting her suspicions, the jury in Elkhorn heard.
In her letter, she addressed notes about drugs and alcohol her husband had written.
Julie Jensen gave the letter to a neighbor with instructions to hand it to police if anything happened to her. She wrote that she would never commit suicide and that if she died, police should consider her husband a suspect. Read the letter »
The letter's use by the prosecutors was controversial, because such evidence has been blocked from court for years by strict hearsay rules giving criminal defendants the right to confront their accusers. But the Wisconsin Supreme Court, guided by a U.S. Supreme Court ruling, created a hearsay exception that permitted the use of Julie Jensen's letter and statements as a dying declaration: evidence of her state of mind at the time of her death.
Jurors said after the trial that the letter proved to be a turning point in their deliberations, which began with five votes for Mark Jensen being guilty, two for not guilty and five undecided.
Foreman Matthew Smith said Julie Jensen's letter brought clarity to the jury on Wednesday night. Watch jurors discuss 'road map to murder' »
The letter, read aloud in court, said in part: "I pray I'm wrong + nothing happens ... but I am suspicious of Mark's suspicious behaviors + fear for my early demise."
The jurors said they compared the letter with a photo of a note found in Mark Jensen's day planner.
Julie Jensen wrote that her husband's note seemed suspicious because of its references to drugs and alcohol. She wrote that she did not drink, smoke or take drugs.
"It was a clear road map; it was totally and completely clear," Schott said.
"You can see where she was taking things from the Post-it note and incorporating it into her letter. It all just fell together for me, and it became very clear to me that Mr. Jensen had murdered his wife."
Jurors also said they rejected the defense's theory that Julie had committed suicide, even though some of them felt that she was depressed.
Prosecutors had offered evidence regarding Internet searches they say Mark Jensen conducted about antifreeze poisoning. Defense attorneys argued that Julie had made the searches in an attempt to frame him for her suicide.
Jurors said they did not believe that Julie Jensen had made the searches because they happened close to times when stocks were traded via the Internet, an activity they ascribed to Mark Jensen, who was working at a stock brokerage firm.
Julie Jensen's brother Larry Griffin said after the verdict that he and his three brothers were happy with the jury's work.
"They saw who she was and why she wrote that letter," he said.
Asked what they would say to Julie if they could talk to her now, one juror said, "I'm sorry it took 10 years." E-mail to a friend