Ahmed Mansour Karni received the lengthy prison term after he was convicted in absentia of four counts of murder, eight of attempted murder, vandalising property, disturbance of peace and threatening police officers - all before his second birthday.
Karni, who was sentenced in a Cairo court this week, is among 115 defendants who were all given life sentences at the same time for crimes allegedly committed in early 2014 in Fayoum province, 70 kilometres south of Cairo.
"It appeared that the court did not transfer the material," Faisal was quoted as saying by media reports.
"The child Ahmed Mansour Karni's birth certificate was presented after state security forces added his name to the list of accused, but then the case was transferred to the military court and the child was sentenced in absentia in an ensuing court hearing," he said, adding that, "this proves that the judge did not read the case".
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Head of the Fayoum Security Directorate Naser el-Abd said the name of the uncle of the child was mistaken for the child.
It is unbelievable that the police arrested a child of this age, he said, adding that the child's uncle, Ahmed Karni Ali Sharara, is wanted in four cases including belonging to an outlawed group, protesting without permission and torching a police vehicle, according to el-Tahrir newspaper.
The sentencing also sparked social media furor, with users lambasting the Egyptian legal system and government of corruption and injustice.
It comes less than a year after a blind man received a 15-year prison sentence for shooting a police officer.