Opening arguments are set to begin on Tuesday in the retrial of Karen Read, the Massachusetts woman who is accused of killing her boyfriend, a Boston police officer, in 2022.

Ms. Read’s first murder trial transfixed the city last year, but it ended in a mistrial in July when jurors failed to reach agreement on a verdict. After the mistrial, her lawyers argued in court that the charges should be reduced.

The court did not agree, so Ms. Read once again faces three charges in the death of her boyfriend, John O’Keefe: second-degree murder, manslaughter while operating under the influence of alcohol, and leaving the scene of an accident causing death.

The case has attracted a wide audience of conspiracy theorists and true-crime aficionados who closely followed the three-month first trial in Norfolk County Superior Court last year.

Prosecutors argued that Ms. Read, 45, intentionally backed her car into Mr. O’Keefe and killed him after a night of drinking. Lawyers for Ms. Read said Officer O’Keefe was killed by people at a party, at a home owned by a fellow Boston police officer, and that law enforcement officials framed Ms. Read to cover it up.

Ms. Read’s supporters staged daily protests outside the courthouse during the first trial, wearing pink and carrying “Free Karen Read” signs. Many continued to protest around the region in the months after the mistrial; a “Free Karen Read” sign popped up in the stands behind home plate during a Red Sox spring training game in Fort Myers, Fla., in February.