"The Police Security Service received tips about the suspect about a year ago. According to this information, the PST and the police conducted an inspection and found no reason to work further [on the matter]", the PST chief said at a press conference.
Norwegian Police Security Service (PST) Chief Hans Sjovold also noted that the tips received by the intelligence services were unclear and unrelated to the planning of the attack.
Philip Manshaus appeared at a court hearing on Monday where he was accused of murder and committing an act of terrorism.
On Saturday evening, the 21-year-old opened fire on Al-Noor Islamic Centre in the municipality of Baerum near Oslo. The incident happened as Muslims across the world were preparing to celebrate Eid al-Adha, one of the most important holidays in Islam. At least one person was injured in the attack. Police specified that the man acted alone. He was subdued by worshipers before officers arrived. Police later found a dead woman in his house, who turned out to be his stepsister.