The gunman in last week’s massacre in Dayton, Ohio, texted his sister and another victim minutes before the shooting, the Dayton Police Department said in a news conference on Tuesday. The police also said the gunman was obsessed with mass shootings, but they declined to say what motivated the attack.

With the help of extensive video surveillance, the police offered an updated timeline of the gunman’s movements and actions in the hours before he killed nine people and wounded 17 others outside a bar in the city’s popular Oregon entertainment district on Sunday, Aug. 4.

The police said the gunman went to the district on Friday night and returned with his sister and a friend at 11:04 p.m. on Saturday. “He was not unfamiliar with this territory,” Chief Richard S. Biehl said.

After visiting a bar with them, the gunman left after midnight, the officials said, walking past a police vehicle to go to his car. They said he went there about 15 minutes before the shooting to retrieve an AR-15-style rifle, ammunition and body armor. He returned wearing a dark hoodie and carrying a backpack, which contained the weapon, they said.