Ex-Coastal Member Seeks Leniency : Justice: Defense lawyers say Mark L. Nathanson has suffered considerably since his extortion conviction. Prosecutors call for a 5-year, 3-month prison term.

Lawyers for a former California coastal commissioner convicted of extortion asked a federal judge Friday for mercy because their client, they say, has suffered to an “unconscionable degree” and his life is in disarray.

In seeking a lighter sentence for Mark L. Nathanson of Beverly Hills, who in June pleaded guilty to extorting payments from Hollywood celebrities and others seeking coastal building permits, the lawyers filed court papers portraying Nathanson as a successful real estate broker whose life has fallen apart since he became the target of a federal political corruption investigation.

U.S. District Judge Lawrence K. Karlton has scheduled Nathanson’s sentencing hearing for Tuesday. Nathanson’s attorneys and federal prosecutors filed sentencing recommendations with the judge this week.

Prosecutors are urging a sentence of five years and three months in federal prison, while Nathanson’s attorneys say he should be sentenced to no more than four years and three months in a minimum-security federal prison camp east of Oakland.

Nathanson’s lawyers say he has been abandoned by friends, forced to sell two Beverly Hills properties and experienced the breakup of a brief marriage.

“He has, at bottom, lost everything a man could lose. There is no point in unnecessarily punishing him any further than the absolute minimum required,” said his Washington-based lawyer Herbert J. Miller Jr.

In exchange for Nathanson’s guilty plea and promise of full cooperation in the ongoing probe of public corruption, prosecutors agreed to drop five of seven criminal counts against him and indicated that they would recommend he serve no more than five years and three months.

Nathanson’s lawyers argue that he should not be sentenced to any more time than former state Sen. Alan Robbins, whose five-year sentence on corruption charges was recently reduced to two years because his cooperation contributed to the indictment of Nathanson and others.

In the prosecution’s memorandum to Karlton, Assistant U.S. Atty. Geoffrey A. Goodman denounced Nathanson’s abuse of public office and urged the judge to impose the five-year, three-month sentence, citing a similar recommendation from a probation officer.

When he entered his guilty plea, Nathanson, 54, admitted to using his position as a coastal commissioner in a dozen extortion attempts--some successful and others not.

Goodman said that in March, 1986, within three months of his appointment by Assembly Speaker Willie Brown (D-San Francisco), Nathanson solicited his first bribe and “continued to exploit his office for private gain until the summer of 1990.” Among his intended victims were actor Sylvester Stallone and producer-agent Sandy Gallin.

In his memo, Goodman said it was unfathomable that Nathanson characterized his conduct to a probation officer as “something similar to cutting through bureaucratic red tape.”

Instead, “this was a clear shakedown for a single purpose--to line the defendant’s pockets to fuel his extravagant lifestyle,” Goodman said.