The mother of a Danish student who was beheaded, along with another Scandinavian woman, while hiking in Morocco’s High Atlas mountains has called for the suspected jihadist killers to face the death penalty as their trial neared its end.

In a letter read out by her lawyer in an anti-terrorist court in Sale, near Morocco’s capital, Rabat, Helle Petersen said: “The most just thing would be to give these beasts the death penalty they deserve, I ask that of you. My life was destroyed the moment that two policemen came to my door on 17 December to announce my daughter’s death.”

Prosecutors have already called for the death penalty for the three main suspects in the murder in December 2018 of Petersen’s daughter, 24-year-old Louisa Vesterager Jespersen, and Maren Ueland, 28, from Norway, who were killed near the village of Imlil in the Atlas mountains.

The maximum sentence was sought for 25-year-old suspected ringleader, Abdessamad Ejjoud, and two radicalised Moroccans, although the country has had a de facto freeze on executions since 1993.

Journalists flocked to the court where the trial of the 24 suspects reopened for what could be its last day, in a case that has shocked the North African country. Petitions on social media have also called for the suspects’ execution. The three men admitted to killing the two Scandinavian women.

The prosecution has called for jail terms of between 15 years and life for 21 other defendants on trial since 2 May.

The life sentence has been sought for Abderrahim Khayali, a 33-year-old plumber, who had accompanied the three alleged assailants but left the scene before the murders happened.

The prosecution called for 20 years’ jail for Kevin Zoller Guervos, a Spanish-Swiss convert to Islam. Guervos, the only non-Moroccan in the group, is accused of having taught the main suspects how to use an encrypted messaging service and weapons. His lawyer, Saskia Ditisheim, said in a letter to the Swiss foreign ministry that the most basic rights of Guervos “had been trampled”; Ditisheim regretted that Guervos had not had consular protection.

All but three of those on trial said they were supporters of Islamic State, according to the prosecution, although Isis has never claimed responsibility for the murders.

The three killers of the women were “bloodthirsty monsters”, the prosecution said, pointing out that an autopsy found 23 injuries on Jespersen’s decapitated body and seven on that of Ueland.

Ejjoud, an underground imam, confessed at a previous hearing to beheading one of the women, and Younes Ouaziyad, a 27-year-old carpenter, the other, while Rachid Afatti, 33, had videoed the murders on his mobile phone.

Hafida Mekessaou, for the defence team, told AFP: “We will appeal for mitigating circumstances on account of their precarious social conditions and psychological disequilibrium.” Coming from modest backgrounds and having a “very low” level of education, the defendants lived for the most part in low-income areas of Marrakesh.

Jespersen’s lawyers have accused the authorities of failing to monitor the activities of some of the suspects before the two women had their throats slit while they camped in the isolated mountain area. The brutal killings could have been avoided had authorities heeded information about the behaviour of street vendor Ejjoud, they said.

Ejjoud, the alleged ringleader, who had been convicted for trying to join Isis in Syria, was released early from prison in 2015 and went on to meet former inmates and other individuals without checks by authorities, said the attorney Khaled El Fataoui. He alleged police had been informed of the activities of the group of men but had failed to act.