Two prominent futures market traders who were accused of trying to corner the market in wheat earlier this year are targets of a new federal investigation of fraud in frozen pork bellies futures trading.

Suspecting that phony transactions may have been staged in the bellies trading pits of the Chicago Mercantile Exchange, the Commodity Future Trading Commission is trying to get original copies of futures market orders from 1976 and 1977.

The CFTC intends to use sophisticated handwriting analysis on the records, apparently to try to determine whether orders that supposedly record a trade between two persons were actually written by the same trader.

The "fictitious sales," as the CFTC describes them, could be used to pass money back and forth between two accounts or to give the appearance that a sale was made when non occurred.

The CFTC filed three separate legal actions in U.S. District Court in Chicago on Monday in an attempt to obtain records and testimony for the investigation.

Named as defendants in the cases were Rosenthal & Co., a major Chicago commodities firm headed by Leslie Rosenthal, vice chairman of the Chicago Board of Trade; Alan Freeman, a general partner of Rosenthal & co., and Heinold Commodities Inc., another big futures market firm.

Freeman and Leslie Rosenthal were identified as two of four speculators who last March gained control of almost 90 percent of the contracts for delivery of wheat on the Chicago futures market.

Contending the four were attempting to corner the market and drive up the price, the CFTC ordered an unprecedented suspension of trading setting off a landmark legal battle over the agency's powers to police the futures markets.

Now the federal commodity market regulators are breaking new ground again with their probe of pork bellies, from which bacon is made.

CFTC officials said yesterday they legally are barred from discussing the investigation, but documents filed in the courts in Chicago and the CFTC order initiating the investigation reveal where the agency is looking.

The pork bellies probers are studying alleged "schemes to cheat and defraud customers," the court records reveal. CFTC documents show the scheme allegedly involves "wash sales, fictitious sales or prearranged trades," all illegal under federal law.

CFTC attorney John Troelstrup revealed the plan to use handwriting analysis in court papers explaining why the agency is seeking originals rather than copies of futures orders.

Attorneys for the defendants in the case have so far refused to turn over the originals, claiming in at least one case that the documents sought by the federal investigators were missing.

Freeman refused to answer questions about his pork bellies dealings when he was called before CFTC investigators June 6. Freeman's attorney state that he was declining to answer questions, CFTC lawyers contend Freeman can do that only if he invokes his constitutional right to avoid self-incrimination.

The CFTC asked a federal judge to hold Freeman in contempt of court if he refuses to answer questions; it apparently is the first time the agency has sought to force testimony in a civil investigation, CFTC sources said.

The CFTC's case involving the wheat trading is pending in the Seventh Circuit Court of Apeals.

Also pending against Rosenthal and Co. are a Cftc lawsuit and an administrative complaint over sales of recently outlawed London commodity options by the firm. If the CTFC's position is upheld in those two cases, Rosenthal's right to participate in the futures markets could be revoked and the company could be fined $100,000 each on an unspecified number of charges.