The rape of a second-grade girl (allegedly by her 68-year-old step-grandfather) at Sanchez Elementary School last Thursday came as a shock to everyone who heard about it. A school security camera captured video of the assault. That the suspect, Pedro Hernandez, was on campus under the pretense of bringing the victim her lunch seemed like just another sickening detail in a sickening crime.

But according to the San Francisco Unified School District, Hernandez had been designated by the victim’s family as a “safe person” to visit the child at school. Gentle Blythe, a district spokeswoman, said the suspect was known to the staff at Sanchez as someone who lived with the child, signed documents for her, sometimes dropped her off at school and had been on campus before.

“We rely on families to let us know if a person who has been an active family member is no longer allowed to visit the child at school,” Blythe said.

The names of people the family designates as emergency contacts and authorized to pick up a child from school are kept on individual student emergency cards in the schools’ main offices. The law requires public school employees to undergo criminal background checks, but people designated as “safe” by students’ families are not subjected to any such scrutiny. In fact, they’re not even required to show I.D. when visiting a campus.

“We don’t ask families to show I.D. because we’re trying to create a welcoming environment for families to participate in the school,” Blythe said, adding that some students might have undocumented parents who wish to be involved in their kids’ educations.

But some school staff say that family-member status doesn’t necessarily make someone safe to be around children.

“Some of the people we’re keeping kids safe from are their families,” said Robin Levick, a community health outreach worker at Phillip and Sala Burton Academic High School.

Statistics indicate that he’s right.

According to the California Office of the Attorney General, 80 to 90 percent of child and adolescent victims of sexual assault know their abusers, and almost half of those perpetrators are family members.

“It’s not uncommon that some parents don’t have legal custody because of problems like this,” Levick said. “It can’t be enough to say, ‘I’m this kid’s grandpa.’”

Blythe said that San Francisco schools have a wide range of family considerations, and that a child’s primary caregivers are often adults other than the biological parents. She also pointed out that the district requires children to be supervised by credentialed staff members throughout the school day. The exception to this can be lunch time, when additional, possibly un-credentialed personnel are authorized to supervise kids.

In last week’s incident, it was a teacher’s aide in the yard at Sanchez who quickly noticed that the victim was missing. The aide went looking for the child and came upon the assault in progress in one of the school’s stairwells. That’s when Hernandez stopped what he was doing and fled. His whereabouts are still unknown.

An I.D. requirement might have helped keep Hernandez off campus. Police said he has no driver’s license or state-issued identification card, and they believe he came to the U.S. illegally.

There are no statewide protocols for identifying visitors to public schools, according to Blythe, and the district policy, at least on paper, is scant. In the 174-page SFUSD Student and Parent/Guardian Handbook, a single three-sentence paragraph is devoted to campus visitation:

All visitors, including parents, must sign in at the Principal’s Office and receive proper authorization to be in the school. Visitors may be asked by the school site staff to display their passes as requested. Student visitors must have prior authorization from the home school principal as well as the site principal before entering the school site. (Emphasis added.)

Nowhere does the handbook denote circumstances under which a visitor might be denied access or in which cases staff should require I.D. The district’s honor-system method of screening most campus visitors appears to assume that someone intent on harming a child would never give a fake name.

As a reporter, I’ve had cause to visit San Francisco public school campuses on several occasions. Sometimes the staff was expecting me, sometimes not. I’ve always checked in at the main office, but have never been required to show a press pass or driver’s license.

Went I went to report the story at Sanchez Elementary School last week, just hours after the assault, I was told to write my name on a sign-in sheet. I was given a sticker that said I was visitor 10 minutes before anyone asked to see my press credentials. When I produced a business card (which displays only my name, trade and contact information, no company affiliation), I was invited to continue waiting for the principal to return. When he did, I asked him about the case. He said he couldn’t talk to me about it and went into his office.

I left the room, with my visitor’s pass still stuck to my shirt, and walked around the school, asking adults if they could tell me anything about the crime. They each said they could not speak about it, but nobody asked me to leave, or even to prove who I was. After all, I was wearing a pass.