A 28-year-old man has been arrested on suspicion of vandalizing the Islamic Cultural Center of Fresno on Christmas day, causing investigators at first to suspect a hate crime, police said Saturday.

But relatives of the 28-year-old suspect, Asif Mohammad Khan, came public to say that schizophrenia — and not hatred — led to the unfortunate incident. "It is a case of mental illness," said his sister, Samia Khan. "There's no question about that."

Asif Mohammad Khan has been booked into jail on charges including felony vandalism for more than $10,000 in damage done Thursday to the Islamic Cultural Center and a nearby medical office.

In the search for a suspect, Fresno Police Chief Jerry Dyer had said that the broken windows and bleach poured on an American flag inside the Islamic center appeared to be a hate crime. On Saturday, Dyer said that investigators interviewed Khan, and their theory has changed. "It was obviously not as we thought," said Dyer, adding that police will let FBI agents decide whether hate-crime charges are warranted.

Khan confessed, telling officers he was upset with people at the Islamic center for talking down or bullying him, Dyer said.

Samia Khan said doctors in 2009 diagnosed her brother as schizophrenic, and in the days before the incidents he had not taken his medication. Khan said she joined Fresno police at a news conference to explain her brother's illness. She said her family is part of Fresno's close-knit Muslim community and apologized for her brother.

"We hope you can find it in your hearts to forgive his mistake," the letter said. "Understand the health issue has brought us here today."