It has become a hauntingly routine paradox in the aftermath of horrific shootings.

An assailant leaves piles of evidence that investigators scrutinize. But law enforcement officials are often left with more questions than answers as they seek to determine a motive.

Officials in Minneapolis were bracing for that outcome as they examined the writings and social media posts of the person they say opened fire through the window of a church packed with schoolchildren on Wednesday, killing two.

“We will follow all of the evidence to its logical conclusion,” Brian O’Hara, the Minneapolis police chief, told reporters on Thursday. “This may not ultimately provide the answers that our public is looking for.”

Robin Westman, 23, carried out the attack and died from a self-inflicted gunshot wound, the authorities said. The attacker left behind a lengthy suicide note, journal entries and scribbling on the weapons used in the ambush at the Church of the Annunciation, which is affiliated with an adjacent Catholic school.

The content includes disparaging messages about President Trump, Christians, Black people, Hispanic people, Jews and Israel.

“The shooter expressed hate toward every group imaginable,” said Joseph H. Thompson, the acting United States attorney in Minnesota. “The shooter’s heart was full of hate.”