The Daily Mail revealed the official cause of death following her autopsy: the 30-year-old died from sepsis triggered by an insect bite.

Marissa was found dead by her housekeeper in London on September 11, leaving her parents and twin brothers devastated.

According to the Daily Mail, the coroner’s interim finding was: “Sepsis caused by an insect bite, with underlying vulnerability due to the effects of chemotherapy and HLH.” Marissa had previously battled breast cancer and in 2023 was diagnosed with hemophagocytic lymphohistiocytosis (HLH), a rare disease.

Despite this, the Lemos family is still seeking clarity. “We are all utterly devastated and broken, there are no words. We lost our beautiful Marissa, the pain is unbearable. It is vital to get to the bottom of this. Did they not know that someone with such a fragile medical history could immediately be struck down by sepsis? Sepsis spreads very quickly and can kill you within hours if not treated immediately,” a relative said.

The family claims Marissa was diagnosed with “toxic effect of venom” at UCLH before being discharged, even though her oxygen levels and blood pressure were dangerously low.

“They had the diagnosis and sent her home. A young woman lost her life just hours after being discharged from hospital, where she had been sent as an emergency for care and monitoring,” the same relative added.

As reported earlier by the Daily Mail, Marissa’s parents, Diamantis and Bessy Lemos, have hired lawyers to sue UCLH for medical negligence. A family member stated: “They must find out what killed Marissa… everyone let her down.”

According to the Daily Mail, Marissa’s body will finally be returned to her family today so they can hold funerals in London and Athens before burying her in the family grave in the Greek capital.