DENVER – It began with what one family called an unimaginable loss: Michelle Wilkins, seven months pregnant and excited about becoming a mother, showed up at the Northern Colorado home of a woman who had posted an online advertisement selling baby clothes. There, the authorities say, the woman beat and choked Wilkins and cut her fetus from her womb with a kitchen knife.

But after prosecutors announced that they would not file murder charges in the death of the fetus – a girl who would have been named Aurora – a politically tinged furor erupted over how the legal system draws the boundaries between what is life and what is not when pregnant women are victims of a crime.

The Catholic archbishop in Denver called the prosecutor’s decision not to file murder charges a “travesty.” Small protests broke out denouncing the decision. And Republican lawmakers said they would try to pass a law so that someone suspected of causing the death of “an unborn member of the species” could be charged with homicide.

While most states have fetal homicide laws on the books, Colorado is one of a dozen where prosecutors must prove that a child had been born, and was alive outside the mother, before they may charge someone with killing the child. That was not the case here, said Stan Garnett, the Boulder County district attorney who filed eight other charges against Dynel Lane, the woman accused of attacking Wilkins.

“Many people in the community, and heaven knows I’ve heard from a lot of them, would like me to have filed homicide charges,” Garnett said at a news conference announcing charges of attempted murder, assault and unlawful termination of a pregnancy in the March 18 attack. “However, that is not possible under Colorado law without proof of a live birth.”

Voters in Colorado have overwhelmingly rejected three “personhood” measures that sought to include the unborn as a person or child for legal purposes. Opponents said the redefinition would have criminalized abortion and birth control, and the measure last year failed to gain support of prominent Republicans like Sen. Cory Gardner, who was then a Senate candidate, or the party’s nominee for governor, Bob Beauprez.

But the unfathomable crime against Wilkins, 26, in Longmont stunned people across Colorado and the country, and has revived an emotional debate in heated commentaries online and in the halls of the Capitol here, giving abortion opponents what they hope will be an opportunity to change local criminal laws.

Archbishop Samuel J. Aquila released a pointed statement condemning what he called a denial of justice and urging legislators to change the laws. In an email interview, he said he had been struck by the “brutality and senselessness” of the attack and felt compelled to weigh in.

“There were two victims, but one of the victims won’t receive justice,” he said. “It doesn’t make sense, because we all know the joy and the hope mothers have for their unborn children.”

Bill Cadman, a Republican and the state Senate president, said the kind of change lawmakers were thinking of “completely protects a women’s right to make a choice about her own health.”

“If this isn’t a clear case of murder, nothing is,” Cadman said. “It’s not debatable.”

But the effort to pass such a bill could face stiff opposition from Democrats, who control one chamber of the legislature, as well as from reproductive-rights supporters who fear such measures lay a path toward outlawing abortion or birth control.

Democratic lawmakers here and a spokeswoman for Planned Parenthood of the Rocky Mountains said they could not comment on the Republican efforts because a bill had not yet been introduced. But Democrats said the push for one was a rushed reaction to a rare and horrible crime that could not be applied retroactively to Wilkins’ case.

In 2013, Colorado lawmakers confronted the same question, and reached a compromise law, the Crimes Against Pregnant Women Act, that has now been used in nine cases, including this one. The law created a new felony category, “unlawful termination of a pregnancy,” but did not satisfy those advocates who had called for the state to adopt fetal homicide charges.

“The law is working,” said state Rep. Mike Foote, a Democrat who was a sponsor of the legislation.

Wilkins’ family is posting occasional updates about her condition on a fundraising website decorated with photographs taken during her pregnancy, in which she smiled at her growing belly. The family has said it trusts the criminal justice system, and is struggling to come to grips with the actions of a “deranged woman.”

“We cannot begin to fathom the depths of depravity and evil which drove her attacker,” her family said in a statement. “One life was ended and another was scarred beyond imagination in this senseless act.”

The authorities say that after Lane, 34, attacked Wilkins, leaving her covered in blood in the basement of her home, Lane told her husband she had miscarried, and they went to the hospital with the fetus. Wilkins managed to call rescuers to report the attack, and spent five days in the intensive care unit, family members said.

Lane, a former nurse’s aide, is being held in the Boulder County jail in lieu of a $2 million bond, and has not entered a plea.

Wilkins’ family has said she is with her partner, Dan, at a safe and undisclosed location. They have so far declined interview requests, citing their need for time, privacy and healing. But, through a representative, Wilkins explained why she and her partner had wanted to name their child Aurora.

“We wanted a nature-based name, and Aurora was the first one that we both fell in love with immediately,” Wilkins said. “People used to ask if it was based off of the Disney princess, Sleeping Beauty, and I would reply not the inspiration, but that I hoped she lived up to that name.”

Last week, Wilkins posted a short note on her fundraising page last week, thanking people for their thoughts and prayers.

“Aurora is a light being now, nothing but ethereal joy and love,” she wrote. “Forever in my heart.”