MILWAUKEE (AP) — A Wisconsin man found guilty of fatally poisoning his wife with antifreeze won an appeal that overturned his conviction, but he remained in prison Wednesday as prosecutors considered whether to seek a retrial.

The 7th U.S. Circuit Court of Appeals panel ruled that a handwritten note from Mark Jensen’s wife, Julie — saying, “if anything happens to me, he would be my first suspect” — was improperly accepted into evidence.

The 2-1 decision said the prosecution’s use of the letter, written two weeks before Julie Jensen’s death, violated Mark Jensen’s constitutional right to face his accusers.

Jensen remains in prison at the Dodge Correctional Institution in Waupun, Wisconsin, because the ruling gives the state 90 days to either release him or move to put him on trial again, said Wisconsin Justice Department spokeswoman Anne E. Schwartz.

The department was considering whether to seek a review from the full 7th Circuit or the U.S. Supreme Court, Schwartz said. If the department doesn’t seek further review, then the Kenosha County District Attorney’s Office would decide whether to retry Jensen, she said.

Jensen’s attorney, Craig Albee, didn’t return a voicemail or email from The Associated Press seeking comment on the case.

Julie Jensen’s body was found in 1998 in the Pleasant Prairie home she shared with her husband and their two sons. Her death, initially considered a suicide, started a case that took more than nine years to go to trial.

Mark Jensen was charged with first-degree intentional homicide, as prosecutors argued that he killed his wife to make room for his mistress and that he searched the Internet for ways to make her death look like a suicide.

The defense said Julie Jensen was depressed and killed herself after framing her husband.

Mark Jensen was found guilty in 2008 and sentenced to life in prison.

(TM and © Copyright 2015 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)