LONDON (AP) — The teenager accused of killing three girls and injuring 10 others in a stabbing attack at a Taylor Swift-themed dance class appeared in court Wednesday to face new charges of possession of deadly poison and terror charges for possessing an al-Qaida manual.

Axel Rudakubana, 18, declined to speak as he appeared briefly at Westminster Magistrates’ Court via video link from prison for the hearing.

Rudakubana, who is also accused of killing three girls and stabbed 10 other people on July 29, was charged on Tuesday with causing the ricin poisoning that was found in a search of his home, Merseyside Police said. Police also found a document on his computer that included an al-Qaida training manual titled: “Military Studies in Jihad Against Tyrants.”

Ricin is derived from the castor plant and is one of the deadliest toxins in the world. It has no known vaccine or antidote and kills cells by preventing them from making proteins.

Rudakubana was charged in August with the stabbing in the Southport community, which police stressed on Tuesday was not being classified as a “terrorist incident” because the motive was not yet known. Police on Tuesday issued the new charges of producing a poison and possessing a terrorist manual.

The stabbing happened during the first week of summer vacation, when about two dozen young girls were dancing to music by Swift at Hart Space, a community center that hosted everything from pregnancy workshops to women’s boot camps.

Rudakubana has been charged with three counts of murder in the deaths of Alice Dasilva Aguiar, 9, Elsie Dot Stancombe, 7, and Bebe King, 6, in the seaside town of Southport in north-west England.

He was also charged with 10 counts of attempted murder for the eight children and two adults who were seriously injured. Leanne Lucas, who was leading the class, and John Hayes, who worked at a nearby business and ran to help, were credited by police with trying to protect the children.

The stabbings fueled far-right activists’ anger at immigrants and Muslims after social media falsely identified the suspect — then unnamed — as an asylum seeker who had recently arrived in Britain by boat.

Hours after a community vigil to mourn the victims in Southport, an unruly mob attacked a mosque near the dance studio and threw bricks and beer bottles at law enforcement officers and set fire to a police van.

Riots spread to England and Northern Ireland that it lasted a week. More than 1,200 people were arrested for the disorder and hundreds were imprisoned.

Rudakubana was born in Wales to Rwandan parents, police later said. British media reported that he was raised Christian.