Police investigators have found a recording on Abdul Ballout's cellphone in which he swears allegiance to the terrorist organization ISIS. The video is said to have been recorded on the same day as the attack.
Such recordings are considered common before a terrorist attack. ISIS supporter Anis Amri, who drove a truck into a Berlin Christmas market in 2016, killing 12 people, recorded a similar video.
The cellphone with the recording was found in the van Ballout used in the attack. Next to the phone was a case for the machete he is believed to have used to attack more people after leaving the vehicle.
A Polish woman was killed and around 30 people were injured in Saturday's attack, which is being investigated as an Islamist terrorist attack.
The following day, Ballout was shot dead by police in a suburban area on the outskirts of Berlin.
Ballout, a German citizen with Lebanese roots, was well known to the judiciary and traveled to Lebanon last year in an unsuccessful attempt to fight for ISIS.
