Coastal Official’s Home Also Searched by FBI : Corruption probe: The residence of Commissioner Mark Nathanson was raided at the same time as Sen. Alan Robbins’ home, an attorney said.

At the same time that the FBI raided the home of Sen. Alan Robbins (D-Tarzana) last week, federal agents searched the Beverly Hills home of California Coastal Commissioner Mark L. Nathanson and seized financial and personal documents, his attorney said Monday.

In conducting the second raid, federal authorities confirmed that they were adding Nathanson to the list of public officials being investigated as part of a widening probe of political corruption.

As reported earlier by The Times, federal authorities have been investigating allegations that Nathanson and Robbins were part of an elaborate scheme to extort $250,000 from a San Diego hotel developer--charges emphatically denied by attorneys for both men.

Nathanson refused to comment on the search.

His attorney, Robert L. Shapiro, stated: “Basically they seized checks, ledgers, (Nathanson’s) Rolodex, his phone directory and business records, all of which would have been provided voluntarily and all of which contained information which was contained in public filings.”

Shapiro said Nathanson “has complied with all aspects of (state) reporting requirements and has violated no laws of the United States.”

The attorney said he did not know the timing of Friday’s search, only that it took place in the morning. Tom Griffin, a spokesman for the FBI’s Sacramento office, said, “We did search Nathanson’s house simultaneously with Sen. Robbins’.”

Griffin acknowledged that the timing showed that the federal agents were investigating a connection between the two men.

Shapiro dismissed the significance of the warrant, contending that obtaining one is “a common practice when they investigate allegations that involve financial dealings.” He pointed out that prosecutors only needed to show that there was probable cause to believe that a crime had been committed to obtain the warrant from a federal judge. He said that that was a far softer standard than the “beyond reasonable doubt” required for a conviction. “I’m not concerned by it, or surprised by it.”

Nathanson, 51, is a real estate broker with longstanding ties to a number of top political officials, including Robbins and Assembly Speaker Willie Brown (D-San Francisco). It was Brown who appointed Nathanson to the Coastal Commission, despite the objections of environmental groups and others who objected to Nathanson’s background in development.

Nathanson has had difficulties with authorities in the past. In 1974, after giving up his seat on the Los Angeles Building and Safety Commission, he was charged with grand theft for allegedly accepting $2,500 from a Hollywood businessman who was seeking a zoning change. Nathanson pleaded no contest to the charge, but insisted that he had acted properly and had not solicited a bribe. The judge reduced the charge to a misdemeanor and sentenced him to three years’ probation.

Federal authorities began investigating Nathanson when a San Diego hotel developer, Jack Naiman, told them that the coastal commissioner and Robbins put him in “a squeeze” in an effort to get him to pay $250,000.

At the time, in 1987, Naiman was developing property in La Jolla that included a Hyatt Hotel and was hoping to block construction of a competing project, a Sheraton hotel, which required approval by the Coastal Commission.

According to Naiman’s allegations, he immediately dropped his opposition to the rival hotel after money was demanded, but Robbins told him that he would have to pay anyway if he wanted to continue doing business in California.