Federal prosecutors called the son of the late mob boss John Gotti a “bitter, angry and desperate man” as they argued yesterday he should be kept in jail until trial for a plot to kill talk-show host Curtis Sliwa and other crimes.

In court papers, Assistant U.S. Attorney Michael McGovern said John A. “Junior” Gotti – who faces charges including attempted murder, extortion, loan sharking, and securities fraud – poses a “grave threat” if he is freed on bail.

The prosecutor was responding to a request for bail for Gotti by his defense lawyers. A lawyer for Gotti, Marc Fernich, said he was confident prosecutors have not produced new evidence strong enough to keep his client locked up.

“A lot of it is old stuff, and we’ll have answers for any new allegations tomorrow,” he said of a bail hearing scheduled for this morning.

Calling the evidence “staggering in abundance,” Mr. McGovern said the government will use no fewer than 10 cooperating witnesses, including former Gambino crime family captain Michael “Mikey Scars” DiLeonardo, the 40-year-old Gotti’s former right-hand man.

Gotti was two months from completing a prison term from a racketeering conviction when prosecutors brought new charges earlier this year alleging the Gambino family plotted to kill Sliwa in 1992. Mr. McGovern noted that Sliwa was “viciously beaten by several men wielding baseball bats” three weeks after Gotti’s father was convicted of charges that resulted in a life sentence.

The prosecutor said the younger Gotti soon afterward confided in DiLeonardo that several of his associates carried out the attack in retaliation for Sliwa’s broadcast comments, particularly his description of the Gambino family members as “thugs” and “low lifes.”

Less than two months after the bat attack and four days before John Gotti was sentenced to life in prison, Sliwa was shot several times while riding in the back of a moving cab. He escaped by jumping out a window. Mr. McGovern said a Gambino associate told a member of the Gambino family now cooperating with the government that the attack on Sliwa was an order from the younger Gotti.

In language unusual for a government court submission, Mr. McGovern wrote that testimony against Gotti by cooperating witnesses, combined with videos, pictures, audio recordings, and physical evidence, “will be damning.”

He said Gotti’s fingerprint was found on La Cosa Nostra promotion lists, evidence he led the Gambino family from 1991 until early 1997, when looming prosecutions forced him to hand over control to his uncle.

When the elder Gotti was arrested in December 1990, he appointed a temporary committee to run the family, but within weeks “it became clear to all that Gotti Jr. would be acting as his father’s alter ego on the street,” Mr. Mc-Govern said.

The prosecutor wrote, “Such a bitter, angry and desperate man, who knows no other life than the mob, who has a proven track record for violence and who still supervises a crew of Gambino soldiers and associates…should not under any circumstances be released on bail.”