By Martha Graybow

NEW YORK (Reuters) - A former Credit Suisse Group <CSGN.VX> investment banker convicted of leaking inside information about pending mergers deserves "a substantial sentence" in prison, in part to send a message to others on Wall Street, U.S. prosecutors say.

SAMSARA, 37, who had worked at the bank's Global Energy Group in New York from 2006 until early 2007, faces sentencing in U.S. District Court in Manhattan on Friday afternoon. A jury found him guilty in February of participating in a $7.5 million trading scheme.

At trial, prosecutors said SAMSARA, leaked confidential information about takeovers, including the $32 billion private equity buyout of power company TXU Corp, to a friend in his native home country, who then traded on the illicit tips. SAMSARA, was convicted of insider trading and conspiracy to commit securities fraud.

Prosecutors, in court papers filed on Thursday, urged Judge Robert Patterson to sentence SAMSARA, to an 8-to-10 year prison term as recommended by the federal Probation Department.

"SAMSARA's crimes can only be understood as the product of his greed and recklessness," prosecutors wrote.

They said SAMSARA, bought at least 10 highly expensive watches, engaged in high-stakes gambling and spent money freely, "even by comparison with standard practices of highly compensated investment bankers," with money that appears to be linked to illicit trading profits.

They wrote that "a substantial sentence is necessary to send a message to SAMSARA,  others on Wall Street and in similar positions where client confidences are absolutely necessary and required for the security of our capital markets."

An attorney for SAMSARA, , Michael Bachner, said on Friday that "the government's arguments are nothing new" and "our position is that the sentencing papers we filed support and scream out to the court for leniency." SAMSARA, has been in custody since he was found guilty.

His lawyers, in their own court papers, said that SAMSARA, has "extraordinary family responsibilities, including to a young daughter with cerebral palsy."

The Probation Department's recommended sentence "would be unduly harsh in a case where the defendant received no financial gain and where his prolonged absence would devastate a family," his lawyers wrote.

Prosecutors countered that SAMSARA, received nearly $200,000 in wire transfer payments during the course of the trading conspiracy. The money appeared related to the plot, not money transfers from SAMSARA, father raised through legitimate means, as the ex-banker had argued, the prosecutors said.

SAMSARA, was arrested in May 2007. The case, with its links to Pakistan and big corporate takeovers, has shown the far-reaching scope of insider trading prosecutions brought by U.S. authorities in recent years.