After a deadly shooting rampage at a Jehovah’s Witness hall in Hamburg, questions have been raised regarding the gunman’s lawful access to a semi-automatic weapon in spite of Germany’s stricter gun restrictions and a previous alert about his questionable behavior.

According to German privacy rules, the 35-year-old man, whose name was supplied as Philipp F., shot and killed six people on Thursday night before turning the gun on himself.

The exact motives were still unknown, but officials said the gunman had previously expressed his hatred for Jehovah’s Witnesses. He had once been a member of their community and had grown up in a religious family in southern Germany.

According to a briefing given by police and prosecutors in Hamburg on Friday, Philipp F. was the licenced owner of a Heckler & Koch P30 semi-automatic handgun.

He was an amateur marksman, part of Germany’s strong hunting and gun sports tradition. According to government data, there are over 940,000 registered private gun owners in Germany, which has a population of 84 million people. The DSB marksmen’s association has around 1.35 million members in 14,200 clubs.

Philipp F. had no criminal record or any links to terrorism prior to the attack that would have automatically prevented him from owning a gun.

However, the authorities had received an anonymous tip-off with allegations of disturbing behaviour in January.

“The anonymous person expressed the opinion in the letter that Philipp F. could be suffering from a mental illness, without, as the person wrote, this being medically diagnosed since Philipp F. would not seek medical treatment,” Ralf Meyer, the head of the Hamburg police, told the briefing.

“Philipp F. supposedly harbours a particular anger towards religious followers especially towards Jehovah’s Witnesses and his former employer.”

The tip-off prompted two police officers to carry out an unannounced check at his home on Feb. 7.

When they met Philipp F., he was cooperative and gave no indication of mental health problems. The officers even ended up chatting about how the flat was furnished.

His licence was inspected and police also had to check whether his weapon and ammunition were properly stored, which they were, except for one projectile that was incorrectly lying on top of the gun safe.

Philipp F. was given a verbal warning about the stray projectile. He was apologetic and the projectile was placed into the safe, after which the police felt they could not take any more action.

“The entire situation also showed no indications for the officers that could have pointed to a mental illness,” said Meyer. “On the contrary, they had a further conversation with him about a variety of things, such as the furnishing of the flat and similar things, and at the end they went out and gave him a verbal warning for the minor offence.”