“We don’t have any information to believe that the family had any knowledge of these events,” Detective Fugitt said. “They’re having a difficult time. This is certainly a shock to the conscience.”

Family friends, neighbors and former classmates were at a loss to explain why Mr. Conditt had carried out the attacks, how he had learned about bomb-making or whether he was driven by racial animus. The first bombs hit members of African-American families who were well known locally, killing a 17-year-old boy and a 39-year-old man. Mr. Conditt was white.

Mr. Conditt grew up as the quiet, socially awkward oldest child of a devout Christian family that held Bible study groups in their white clapboard house, where an American flag hangs from the front porch.

After Mr. Conditt, 23, was identified on Wednesday as the serial bomber who killed two people and terrorized Texas’ capital, Mr. Conditt’s mother sent a text message to a friend, Donna Sebastian Harp. It said: “Pray for our family. We are under attack” — a reference to a spiritual assault.

“It’s a Christian-ese thing we say,” Ms. Harp said. “Pray: the situation is very serious.”

Governor Abbott told the television station KXAN that Mr. Conditt did not have a criminal record, had not served in the military and was unemployed. He said it appeared that Mr. Conditt had acted alone, but authorities had not definitively ruled out whether he had any accomplices.

In 2012, Mr. Conditt hashed out some of his views on a blog that he created for a political science class while he was a student at Austin Community College. Jessica Vess, a college spokeswoman, said that Mr. Conditt had attended from 2010 to 2012 as a business administration major.