A Colombian businesswoman has been accused of killing two schoolgirls by gifting them poisoned chocolate-covered raspberries as an “act of vengeance” after a failed affair with the father of one of her alleged victims. An Interpol Red Notice – like an international arrest warrant – has been issued for Zulma Guzman Castro after she was named by public prosecutors who want to question her over the deaths of Ines de Bedout, 14, and her 13-year-old friend Emilia Forero.

The two youngsters died in hospital after eating the dessert laced with thallium, a colourless and odourless heavy metal, initially linked to the poisoning of former Russian spy Alexander Litvinenko, who died in a London hospital in November 2006.

Forensic experts have determined the heavy metal – which can be lethal in tiny doses – was deliberately injected into the raspberries before they were delivered to the luxury apartment in the Colombian capital, Bogota, where the victims had been playing after school. After tests pointed to the youngsters being murdered, Colombia’s prosecution service asked Interpol to arrest university graduate Guzman, said to have fled her homeland for Argentina following the girls’ deaths.

Local reports are pointing to the double homicides being a possible crime of passion because the wanted woman, who founded a car-sharing company called Car-B, had an affair with Ines’ dad, Juan de Bedout. Colombian daily El Colombiano also claimed that investigators are now probing the death of Juan’s wife amid speculation that two years before the schoolgirls were targeted, she too could have been the victim of thallium poisoning.

Guzman, who is protesting her innocence, is understood to have spent time in Brazil, Spain and the UK since leaving Colombia earlier this year.

She claimed in a message: “I find myself in the middle of a very serious situation, where I’m being accused of having been the person who sent a poison that killed two girls.

“They accuse me of having fled to Argentina, and then to Brazil, Spain and the UK. Those who know me know I haven’t fled anywhere. They know I’ve been working in Argentina and began a masters in journalism here. I went to Spain more than a month ago, with a stopover in Brazil, and then to the UK because of my son. I imagine they’re accusing me because I had a secret relationship with the father of one of the girls.

“Public prosecutors have never informed me about any investigation and I sent a lawyer friend of mine yesterday to ask, because I heard rumours people were talking about me. The following day my name is in the media. I hope those that know me support me and defend me.”

The Red Notice orders police in Interpol’s 196 member countries to locate and detain Guzman, whose current whereabouts are unclear.

The two schoolgirls died at Bogota’s benchmark hospital, Santa Fe de Bogota Foundation, just under a week after they were poisoned on April 3. Another friend and the 21-year-old brother of one of the victims were also hospitalised after eating the raspberries but survived, although the girl who cheated death is understood to have suffered lasting injuries.

Prosecutors allege Guzman, who left Colombia on April 13, used a courier firm to deliver the fruit dessert. The deliveryman has told investigators that he was given the package containing the raspberries by a friend of the fugitive and was advised that it was a present for them because the dessert was one of their favourites.

Guzman has been described as a long-term friend of Ines de Bedout’s family who knew their daily routine and was aware the youngster loved chocolate-covered raspberries. The package was delivered to the girls just after 7pm local time on April 3, after they reportedly rejected an earlier attempt to hand it to them, saying they weren’t expecting anything.

The father of one of the girls allegedly killed in the “act of vengeance” has said he cannot comprehend her actions in an emotional tribute to the 13-year-old. An agonising social media post published by Emilia’s devastated father, Pedro, emerged overnight as the youngster was pictured for the first time.

Pedro, speaking shortly before it emerged Colombian prosecutors have a suspect for the horror crime, said: “Fourteen years ago, a life of hopes, joys and dreams began; a life that filled a family, a father and a mother. But it wasn’t just the joy of someone else’s life; it was the beginning of the life of an excellent human being who had dreams, hopes and goals.

“As a father, it is incomprehensible to think that someone was capable of taking this away. She did not just take away my dreams, my desires and my prospects in life as a father; she did not just take away my opportunity to be a father-in-law, grandfather and everything else one can be as a parent.

“She took away my daughter’s opportunity to be a girlfriend, a professional, a wife, a mother and a daughter.”

In a gut-wrenching message alongside a photo of Emilia as a baby, he added: “Daughter, you will always be the greatest love I could ever feel as a father. No girlfriend or wife could ever generate the love I felt when I had you, and I will carry this love with me until the last day of my life.

“I love you and will love you for the rest of my life. I mourn the stories we will never be able to live. I am grateful for who you were and what you taught me. You were and will always be the most beautiful thing I ever had in my life.

“I love you. I miss you. I am sorry I could not protect you from this broken world. Despite the pain, I am glad to have had you in my life. I hope to have one last hug from you, even if it is only in my dreams.”