The US government, a staunch ally of Morocco, has repatriated nine Moroccans from Guantanamo Bay since August 2004 and all of them were put on trial.
Many of the inmates at Guantanamo were captured by US-led forces fighting the former Taliban government in Afghanistan.
Moroccan analysts say relatively few people from the North African kingdom fought for the Taliban, compared to the number of fighters from Egypt and the Gulf states.
Four Moroccans remain at the maximum-security prison, according to the government, although rights activists say there are more.
Mohamed Darif, a Moroccan political analyst said: "The fact the Americans released the five from Guantanamo already proves their innocence."
He said there may also have been less pressure to find the five guilty than after the September 11, 2001 attacks in the US and suicide bombings in the Moroccan coastal city of Casablanca in 2003.
The Moroccan authorities say they have broken up more than 50 radical Islamist cells and rounded up thousands of people since the 2003 attacks, which killed 45 people.
Earlier this month the government said it had dismantled a radical Islamist cell recruiting volunteers to fight in Iraq and arrested 26 people.
In November, three former Guantanamo detainees were convicted in Morocco for creating a criminal group and forging documents, and sentenced to three to five years in prison.
Moroccan human rights groups recently said a total of 10 Moroccan detainees at Guantanamo had repatriated.