(CNN) — A federal court has denied a 19-year-old’s request to let her witness her father’s execution on Tuesday, when the state of Missouri is scheduled to put him to death for the 2005 murder of police sergeant William McEntee.

Corionsa Ramey is barred from attending the execution of her father, Kevin Johnson, because Missouri state law prohibits people younger than 21 from witnessing the proceeding. Ramey and attorneys from the American Civil Liberties Union argued the law violated her constitutional rights under the First and Fourteenth Amendments, according to her complaint against state officials — which asked the court to prevent the state from executing Johnson unless Ramey was permitted to attend as a witness.

“I’m heartbroken that I won’t be able to be with my dad in his last moments,” Ramey said in a statement shared by the ACLU. “My dad is the most important person in my life. He has been there for me my whole life, even though he’s been incarcerated.”

Though he was charged with McEntee’s murder when his daughter was just 2 years old, Johnson has remained an involved parent, Ramey wrote in an affidavit to support her lawsuit, thanks to regular visits, phone calls and email. Just last month, Ramey brought her newborn son to the prison to introduce her father to his grandson.

But while a federal judge acknowledged in his ruling the potential for Ramey to suffer “emotional harm,” he rejected her arguments, finding the state had a “substantial interest in the sovereignty of its criminal law enforcement.”

Corene Kendrick, deputy director of the ACLU’s National Prison Project and one of Ramey’s lawyers, said in a statement her legal team was “extremely disappointed in the decision upholding this irrational and illogical law, which only serves to gratuitously punish Ms. Ramey.”

Attorneys for Johnson, 37, are separately seeking a stay of execution, claiming racial discrimination played a role in his prosecution, conviction and death sentence; the Missouri Supreme Court is set to hear that case Monday. That claim is supported by a special prosecutor recently appointed on behalf of the St. Louis County Prosecuting Attorney, who wrote in their own motion for a stay that “purposeful racial discrimination infected” the process, not only in Johnson’s situation but in others in which the defendant was Black and the victim a police officer.

Johnson’s attorneys have also asked Missouri Gov. Mike Parsons to grant Johnson clemency, but the governor indicated to CNN affiliate KMOV last week his office intends for the execution to proceed as planned.

“You got a guy who went over there, cold blooded killed a police officer by two shots in the head after he shot him multiple times,” the governor said. “It’s a pretty vicious crime. Sometimes you have to answer the consequences to that.”

Johnson was 19 — the same age his daughter is now, her attorneys noted — when he fatally shot McEntee, a police sergeant for the Kirkwood Police.

Earlier on the day of the killing, Johnson’s 12-year-old brother died after having a seizure at their family’s home, according to court records. Police were there at the time of the seizure, seeking to serve a warrant against Johnson for a probation violation.

Johnson blamed the police, including McEntee, for his brother’s death. And hours later, as McEntee responded to a report of fireworks in the neighborhood, Johnson approached the sergeant’s patrol car, accused him of killing his brother and opened fire.

McEntee, a 20-year veteran of the Kirkwood force, was 43 years old, according to the Officer Down Memorial Page. Among the family he left behind were a wife, a daughter and two sons.

‘A new and fresh loss’

Generally, the 27 states that practice capital punishment allow a certain number of witnesses to attend executions, including members of the victim’s family, the inmate’s family and members of the press. In Missouri, as the condemned, Johnson is allowed to choose up to five witnesses, but state law barred his daughter from being one of them because of her age.

Missouri — where executions have become increasingly rare, with just one or zero executions each year since 2016, per the Death Penalty Information Center — is not alone in barring people of certain ages from witnessing executions.

In California, where a moratorium on the death penalty is currently in effect, no one under the age of 18 is allowed to witness. Tennessee similarly bars members of the victim’s family under the age of 18, and in Oklahoma, witnesses for the victim and the inmate must also be 18 or older.

But Ramey’s relationship with her father underscored her “abiding interest in witnessing her father’s execution,” her complaint said.

Two years after her father was charged with McEntee’s murder, Ramey’s mother was killed, she wrote in her affidavit, leaving Johnson as Ramey’s only living parent.

Since then, Johnson and Ramey have worked to maintain a father-daughter relationship, despite his confinement on death row, she and her attorneys said in her complaint. Ramey would visit Johnson “as often as family and friends were able to take me to see him, and I speak to him by phone at least once a week,” she wrote in her affidavit. When she can afford it, they correspond via email through the prison communication service JPay.

Johnson’s involvement is illustrated, Ramey and her attorneys said, by the fatherly advice he’s given her over the years and his support of his daughter’s education, including arranging for an academic liaison to keep him updated on her grades, which he monitored closely until she graduated two years ago from high school. He continues to encourage her as she tries to become a nurse, they said.

Two months ago, Ramey gave birth to a son, and her father has been her “biggest source of support, advice, and love as I navigate adjusting to being a new mom,” she wrote.

In October, she took her son to meet her father, she writes. “My father was able to hold his grandson, and we were able to get a photograph taken together,” she said. “It was a beautiful but bittersweet moment for me, because I realize that it might be the only time that my father would get to hold my son.”

Prior to the denial by the federal court, Kendrick called the Missouri law barring people under 21 from witnessing executions “illogical and irrational,” adding, “If the State of Missouri thinks that her father’s actions when he was 19 make him mature enough to warrant execution, then a 19-year-old should be mature enough to witness that execution.”

“I have suffered so much loss in my life thus far,” Ramey said in her affidavit, referencing both her father’s incarceration and her mother’s killing. “It is excruciating to know that I am about to lose my father all over again when the State kills him, yet I cannot be present for his death simply because of my age.”

“The fact that I will not be able to give him comfort, and experience any sort of grief or closure for myself, for no other reason than I am 19 years old, is a new and fresh loss,” she said, “a total injustice.”

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