Mechkah, an asylum seeker from Morocco who was living in a refugee center, is now in hospital recovering after being shot by police.
An 18-year-old Moroccan asylum seeker was arrested after police shot him in the leg.
His alleged crimes are being treated as murder and attempted murder with terrorist intent, a court in Finland said Monday.
Finland's state broadcaster YLE reported Mechkah's name, citing court documents, and said he would appear in court via video link Tuesday.
The attack happened in the Puutori/Market Square area of Turku just after 4pm local time, with police receiving reports of a man attacking passers-by with a knife.
No group has claimed responsibility for the attack, though police are investigating possible links to Thursday's van attack by suspected Islamist militants in the Spanish city of Barcelona where 13 people were killed.More news: Total To Pay $7.45bn for Maersk Oil
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The two people who were killed in the attacks were Finnish citizens.
Four Finns, an Italian and a Swede were also injured in the attack, which Finland's Security Intelligence Service said was "a likely terror act".
The assailant appeared to have targeted women, police have said.
In addition to the arrest of the main suspect four other Moroccans have been held and an worldwide search warrant issued for a sixth individual.
Among the injured was Hassan Zubier, 45, a paramedic who was born in Dartford, Kent.
The British man was stabbed repeatedly while he helped victims of the attack.