New details about the police case against the alleged Bondi terrorists have been released, including details of an alleged video manifesto linked to the Islamic State and the undetonated explosives – including a “tennis ball bomb” – found at the scene.

Naveed Akram, 24, faces charges of murdering 15 people and injuring dozens more in the shooting at a Hanukah celebration on 14 December. His 50-year-old father, Sajid Akram, 50, is the second alleged shooter and died at the scene.

The police “fact sheet” – outlining their allegations against Naveed – reveals investigators believe three pipe bombs and a tennis ball bomb were thrown towards the crowd before the pair began shooting. While they did not detonate, police alleged they were “viable improvised explosive devices”.

Police allege in the court document, released Monday, that there is evidence that the pair “meticulously planned this terrorist attack for many months”.

A video found on the accused’s phone, recorded in October, shows Naveed and his father sitting in front of an image of the IS flag, according to the document.

Police allege that Naveed – appearing with four long-arm firearms – appears to recite in Arabic a passage from the Qur’an in the video, before he and his father go on to make in English several statements about why they planned to commit the Bondi attack, including “condemning the acts of ‘Zionists’”.

Another clip, also recorded in October, allegedly shows the father and son training with firearms in a rural setting, suspected to be located in New South Wales. The clips show them firing shotguns and “moving in a tactical manner”, according to the document.

Naveed and his father are accused of acting in a joint criminal enterprise, with the goal of “causing a person’s death and furthering an extremist political, religious and ideological cause, namely religiously motivated violent extremism aligned with Islamic State”.

The fact sheet was released after lawyers for media companies applied for it to be released.