Prosecutors have called for the death penalty for the three main jihadist suspects behind the "bloodthirsty" murder of the young Scandinavians.
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.
Petitions on social media have called for their execution.
The three admitted to killing Danish student Louisa Vesterager Jespersen, 24, and 28-year-old Norwegian Maren Ueland.
The prosecution has called for jail terms of between 15 years and life for the 21 other defendants on trial since May 2 before an anti-terror court in Sale, near Rabat.
The life sentence has been sought for Abderrahim Khayali, a 33-year-old plumber, who had accompanied the three assailants but left the scene before the murders.
The prosecution called for 20 years in jail for Kevin Zoller Guervos, a Spanish-Swiss convert to Islam.
All but three of those on trial had said they were supporters of the Islamic State (IS) group, according to the prosecution, although IS itself has never claimed responsibility for the murders.
The three killers of the girls were "bloodthirsty monsters", the prosecution said, pointing out that an autopsy report had found 23 injuries on Jespersen's decapitated body and seven on that of Ueland.
Ejjoud, an underground imam, had confessed to beheading one of the girls and Younes Ouaziyad, a 27-year-old carpenter, the other, while Rachid Afatti, 33, had videoed the murders on his mobile.
The defence team said it would call for the judge to take into account extenuating circumstance.
"We will appeal for mitigating circumstances on account of their precarious social conditions and psychological disequilibrium," Hafida Mekessaou told AFP.
Khalid Elfataoui, representing Jespersen's family, said she would read out a "devastating" letter received from the Danish woman's family and demand compensation of 10 million dirhams (just over $1 million) on their behalf.
The Norwegian woman's family has declined to take part in the trial.
'Failure to monitor'
Jespersen's lawyers have accused authorities of having failed to monitor the activities of some of the suspects before the two women camped in an isolated mountain area had their throats slit.
The brutal killings could have been spared had authorities heeded information on the behaviour of street vendor Ejjoud, they said.
The alleged ringleader who had been convicted for trying to join IS in Syria was released early from prison in 2015 and went on to meet former inmates and other individuals without checks by authorities, attorney Khaled El Fataoui said.
He alleged police had been informed of the activities of the group of men from an underprivileged background but failed to act.
Lawyer Houssine Raji added the suspects met in Koranic schools run by cleric Mohamed al-Maghraoui, which had been shut in 2010 under a court decision but ordered reopened in 2012 by the justice minister.
Investigators have said the "cell" was inspired by IS ideology, but Morocco's anti-terror chief insisted the accused had no contact with the jihadist group in conflict zones.