SAN FRANCISCO -- The war of words has heated up several notches in the Christmas Day fatal tiger attack case with the surviving victims attorney -- Peterson defense lawyer Mark Geragos -- proclaiming in a letter to the San Francisco city attorney that Zoo workers told his investigators that the tiger enclosure "couldn't hold a house cat."

In a letter to Dennis Herrera, Geragos said "almost more disturbing then the horrific events detailed above is what our preliminary investigation has uncovered so far. As you must know, prior to the attack the tiger exhibit wall was measured by Zoo employees, who determined that it was only 12 1/2-feet high and, in their words, "couldn't hold a house cat.'"

Geragos also bristled at reports that his clients -- San Jose brothers Paul and Kulbir Dhaliwal -- were not cooperating with police.

"We reject your assertion that our clients have refused to cooperate with the San Francisco Police Department in their investigation of the unprovoked tiger attack on them," he wrote. "In fact, since being retained on the case this office has spoken with SFPD police inspector Valerie Matthews nearly every day. In fact, hours before your letter was leaked to the media, we had already scheduled an appointment for the Dhaliwal brothers to meet with Inspector Matthews."

Geragos was also critical of the actions of Zoo officials and may have tipped his hand as to a potential lawsuit from the brothers.

"As if its near-criminal negligence was not bad enough, the Zoo has now engaged in a vicious, defamatory smear campaign directed at our clients," the attorney wrote. "In an attempt to distract attention from its failure to ensure the safety of its patrons, a so-called crisis management team hired by the Zoo has made repeated media attacks which constitute actionable defamation."

Geragos also wrote he was worried the SF police investigation into the attack was being compromised.

"Moreover, although so far it appears that the SFPD has done a professional job in its investigation, within in the last several days it has become apparent that external sources are exerting improper influence on the department," he wrote. "Specifically, the SFPD has admitted to us that there is no legal authority to retain control of the Dhaliwal's vehicle and cell phones, which were seized and are believed to be in the possession of the SFPD."

"The department initially agreed to release those items to our clients. The very next day, however, that decision was reversed and despite our repeated requests the SFPD has not released them."

Last Friday, Herrera sent a letter to Geragos asking him to instruct the brothers not to tamper with any of their possessions currently being held by police as part of a criminal investigation into the incident. He also proposed a simultaneous inspection of the brothers' car and cell phones by experts hired by Geragos and experts from the city attorney's office.

Herrera said the digital content of the cell phones might help reconstruct what happened at the tiger exhibit, where the brothers' friend Carlos Sousa Jr., 17, was fatally mauled, and at the Terrace Cafe, where the brothers reportedly ran to escape the tiger and where the tiger followed them and was fatally shot by police.

Without naming either the brothers or Sousa, Zoo director Manuel Mollinedo said Wednesday that he believed Tatiana, a 350-pound Siberian tiger, had been provoked somehow into leaping over the tiger exhibit's wall and attacking the three young men.

Both brothers survived the attack with claw and bite wounds.

Herrera said he had learned police asked the brothers for permission to examine images and other contents of their cell phones, and were rebuffed.

"Your clients refused to cooperate with this request," Herrera wrote. "Consequently, no one has examined this potentially critical evidence."

Herrera also cited media reports of evidence in the brothers' car of possible alcohol consumption.

"We trust that you will immediately agree to preserve all of your clients' personal property that may be returned by the police and guarantee that the contents of the phones and car are not destroyed or altered in any way," Herrera said.