NAIROBI, Kenya – A Kenyan court Wednesday found three people guilty of conspiracy to commit a terror attack after phone records and handwriting linked them to the 2015 Garissa University assault that killed 148 people.

Mohamed Abdi Abikar, Hassan Aden Hassan and Rashid Charles Mberesero will be sentenced on July 3, Chief Magistrate Francis Andayi said. These are the first convictions of the attack. A fourth person, Sahal Diriye Hussein, was acquitted. Kenyan court processes take time due to the backlog of cases that the judiciary is working to clean up.

Defense counsel Mbugua Mureithi said he will appeal.

The Garissa University attack saw four gunmen with the al-Shabab extremist group based in neighboring Somalia force their way onto campus. The gunmen were killed. The attack is al-Shabab’s deadliest attack on Kenyan soil. Al-Shabab is al-Qaida’s affiliate in the region. Al-Qaida carried out Kenya’s deadliest attack when it bombed the U.S. Embassy building in Nairobi in the August 1998 killing more than 200 people. The U.S. Embassy in Dar es Salaam was targeted by the group on the same day in a near simultaneous attack.

Al-Shabab has carried out numerous attacks inside Kenya since 2011, calling it retribution for Kenya sending troops into Somalia to counter the al-Qaida-linked fighters. The group attacked a luxury hotel complex in Nairobi in January.