The city attorney sought permission to inspect the car and cell phones belonging to the two brothers who survived tiger attacks at the San Francisco Zoo, but the victims are balking, the attorney said.

Deputy City Attorney James Hannawalt sent a letter Friday to the brothers' lawyer, Mark Geragos, asking him to make sure they preserve any photographs or call logs that were on the phones before the Dec. 25 mauling that claimed the life of 17-year-old Carlos Sousa.

• Click here for photos.

San Francisco police have the phones, but the brothers, Kulbir and Paul Dhaliwal, have refused to authorize investigators to examine the contents, according to Hannawalt.

"Your clients refused to cooperate with this request; consequently, no one has yet examined this potentially critical evidence," he wrote in the letter.

Click here for more from KTVU FOX San Francisco.

Click to read Adam Housley's on-the-scene blog.

Police officials previously have said that an empty vodka bottle was on the front seat of the car the three young men drove to the zoo last week.

Hannawalt proposed having evidence experts from his office and others hired by the brothers inspect the phones and the car together when the police are ready to release it "in the interests of getting to the real facts behind this tragedy."

A message to Geragos' office on Friday was not immediately returned.

Geragos told The Associated Press earlier this week that he wants to get hold of his clients' cell phone records to see if they hold any information that would back up their claim that they tried in vain for over half-an-hour to notify the zoo the tiger had escaped.

City officials have been investigating the fatal attack to determine if the 350-pound tiger, which was shot dead by police, was harassed or teased in any way before she jumped or climbed out of her enclosure.