According to the book Sinimägede sangar
(Hero of the Blue Hills or something like that in English) by Voldemar Pinn there were four other men captured with Maitla. These four were Maitla's aide-de-camp, two other officers and Maitla's chauffeur Arnold Mägar. Mägar survived and he told his story to Pinn in 1998. According to this page by Michal Plavec and Reigo Rosenthal
http://paber.ekspress.ee/viewdoc/D6BFE0 ... 9E0023F502
Mägar had already told the story to Maitla's widow in 1992.
According to Mägar Maitla and his ADC were taken from their cell and shot sometime in the night between May 9th and 10th. When these two men had been killed, the executioners came to take the other two Estonian officers and shot them, too. Mägar, however, managed to hide with the help of German prisoners so that when the Czechs came for him, they could not find him.
Mägar does not remember the names of the three other officers killed, but according to the web-page mentioned above, Maitla's ADC might have been Captain Arved Laasi. According to Pinn, however, Mägar says that Laasi had been succeeded as Maitla's ADC and Mägar says he cannot remember the name of the new ADC. Plavec and Rosenthal also mention that one of the other officers might have been lieutenant Kalju Tamme.