It’s the case that has rocked Spain, sparking protests, triggering an international manhunt, and drawing the attention of the royal family.

A father allegedly drugged and killed his two little girls, put their bodies in duffel bags, and dumped their bodies at sea—all to spite their mother for getting a new boyfriend.

Now, days after the remains of the older child were found off the Canary Islands, her devastated mom is speaking out, saying she hopes the deaths will not be in vain and will lead to more protections for children.

“They are now two angels… teaching a great lesson at the cost of their lives,” Beatriz Zimmermann wrote in an open letter, according to El Periódico.

Her ex-partner, Tomás Gimeno, vanished with 6-year-old Olivia and 1-year-old Anna on April 27, leaving behind a message that Zimmermann would never see them alive again.

Last week, it became clear the message was not an empty threat when search crews found Olivia in a bag, and a second empty bag—weighted down by an anchor—thousands of feet below the water’s surface off Tenerife.

The discovery ignited public outrage at every strata of Spanish society.

“I don’t think there is anyone this morning who is not trying to put themselves in the shoes of the people who love these murdered girls,” Queen Letizia said on Friday.

Spain’s equality minister, Irene Montero, tweeted her condolences with the hashtag #Nomasviolenciavicaria—a reference to abusers harming children as a way to cause their parent pain.

It’s not clear what happened to Gimeno, whose boat was found drifting off Tenerife. A judge on Friday issued a new international warrant for his arrest, declaring that the crime was no longer an abduction but a homicide and that Gimeno’s intention was to kill them “in a planned and premeditated fashion to cause his ex-partner inhumane pain.”

In her anguished letter, Zimmerman thanked the public for its support, blasted “the most monstrous act that a person can commit,” and said she wished she had died with them.

“But that couldn’t be because Tomás wanted me to suffer searching for them without rest,” she wrote. “That was the reason why he left me alive.”