The information accumulated so far in the year-long Justice Department investigation of alleged drug use on Capitol Hill does not warrant criminal charges against any congressmen, according to sources familiar with the investigation.

Those same sources emphasized in interviews last week that the investigation is continuing, and prosecutors are especially interested in questioning two men whose arrest a year ago sparked the drug probe. Both men--Douglas W. Marshall and Troy M. Todd Jr.--went to Australia before they were formally indicted last November on charges of running a cocaine distribution ring on Capitol Hill. They were arrested in January in Australia and are now fighting extradition.

Most of the information against the three past or present congressmen known to be under investigation--Reps. Ronald V. Dellums (D-Calif.) and Charles Wilson (D-Tex.) and former representative Barry Goldwater Jr. (R-Calif.)--is either hearsay or one person's word against another, according to informed sources. Generally, cases involving alleged past transactions, without undercover agents or tapes, are invariably difficult to prove, even with good witnesses, according to law enforcement sources familiar with such investigations.

The three have been the subject of unsubstantiated allegations of purchase or use including cocaine or marijuana. All have denied any wrongdoing, and no charges have been brought against any of them. Possession of small amounts of cocaine or marijuana is a misdemeanor offense punishable by a maximum of one year in prison.

In addition to the Justice Department probe, a separate but parallel investigation into alleged drug use on Capitol Hill is being conducted for the House ethics committee under the direction of special counsel Joseph A. Califano Jr.

The only known formal action taken by the committee against a congressman in the current drug probe was a vote last week to formally open a "preliminary inquiry" into the allegations against Dellums.

The opening of a formal inquiry is a significant stepthat the committee has authorized only a dozen times in the past five years, according to one source familiar with the panel's work.

Califano said last fall that he hoped to complete the drug probe by early this year, but it is now unclear how long Califano and his team of 12 investigators, researchers and lawyers will take to finish their work.

After the initial arrests last April of Marshall, 27, a former House page, and Todd, 23--alleged in the indictment to be the main supplier of drugs to Marshall--the U.S. attorney's office, at the request of top Justice Department officials, decided to break a longstanding policy of not investigating alleged drug users.

Justice Department officials, many reluctant to apply a higher standard to congressmen than to average citizens but sensitive of being accused of a coverup, decided to launch a major investigation of alleged drug use by congressmen, despite having initially only what one law enforcement official called "the baldest, unsubstantiated allegations." Users generally are not pursued because prosecutors have devoted their resources to investigating drug pushers.

Federal authorities are investigating any allegations of drug use by congressmen, no matter how vague those allegations are. Investigators have interviewed scores of witnesses so far, although prosecutors have brought relatively few witnesses to testify before a 23-member federal grand jurythat meets twice weekly to hear testimony in this probe and in numerous investigations unrelated to Congress. That grand jury's 18-month term is scheduled to end in July, but any unfinished business is likely to be forwarded to another grand jury, according to sources familiar with such proceedings.

The allegations against Dellums, made to a federal grand jury by Robert T. Yesh, a longtime employe in the House doorkeeper's office, are that Dellums purchased cocaine on three occasions directly from Yesh. "All we really have against Dellums is Yesh," one source familiar with the federal investigation said. Dellums, through his lawyer, has denied ever buying cocaine from Yesh or anyone else.

Without corroboration, it is unlikely that prosecutors would seek criminal charges against anyone on the basis of Yesh's testimony, that source said, especially since Yesh pleaded guilty to two misdemeanor drug charges and is cooperating with the investigation. Yesh, whose annual salary was $31,739 in January when he was working in the House documents room, submitted his resignation last week, the House doorkeeper's office said yesterday. Reached at his Springfield home, Yesh declined comment.

The Justice Department investigation of Wilson, for alleged cocaine use at social gatherings in Houston and Las Vegas, is continuing. Sources familiar with that investigation said federal investigators have gone to those cities to see if any witnesses corroborate the allegations.

Wilson said the allegations are coming from a man he helped send to prison for fraud, that it is no coincidence his troubles started right after the man got out of jail. The congressman said he has not been told officially by either the Justice Department or the ethics committee that he is under investigation but that a number of friends have told him they have been questioned in regard to the allegations.

"I have been flabbergasted at the lengths to which they Justice Department investigators have gone to find something, anything on me," Wilson said. "I question severely the double standard" used for investigating congressmen. That affects a member even when he eventually is found to be blameless, he said.

"All your friends question you. You can't get a date," he added.

The investigation of Goldwater for alleged drug use, according to informed sources, is essentially complete. The Justice Department official in charge of that investigation has recommended that no charges be brought against Goldwater. The department has taken no action on the recommendation.

The House ethics committee investigation began last summer after congressional pages made unrelated allegations of sexual misconduct against congressmen and their aides. Califano's group was empowered to look into the sex charges and also the separate allegations of congressional drug use arising from the investigation of Marshall and Todd.

Califano announced last December that there was "no merit whatsoever" to allegations of sexual misconduct by congressman, but said that the investigation of alleged drug use by members would continue.

Califano's investigative team follows leads and allegations as they come in and pursues those with the most merit. It looks at members and staff when allegations are made. It has dismissed a number of allegations as frivolous without ever getting to the stage of a formal inquiry, according to informed sources.

A formal "preliminary inquiry" can lead either to dismissal of the case or to a "statement of alleged violation." If such a statement is made, a hearing is held and the committee then votes on whether to recommend disciplinary action. This can include expulsion from the House, censure, reprimand or fine. The full House then votes on the recommendation.

It is unclear why the committee chose at this time to vote to initiate a preliminary inquiry against Dellums. The action was taken in executive session, and members of the committee would not comment on the decision.

Sources familiar with the current Justice Department investigation into the three congressmen liken it to one undertaken in 1980 against Hamilton Jordan, chief of staff to President Carter, involving allegations of using cocaine on two occasions. A special prosecutor and his staff interviewed about 65 people and called 33 witnesses before a special federal grand jury in that investigation before Jordan was exonerated.

Sources familiar with the House probe say the committee is no longer interested in allegations against Goldwater because he is no longer a member of the House. Goldwater gave up his House seat to run an unsuccessful campaign for the Senate last year. "We have never disciplined a former member," a committee staff member said in an interview last week.

Dellums' attorney, Michael E. Tigar, met with Califano Thursday to try to get details on the allegations. Tigar has been unavailable for comment since the meeting but his law partner, Samuel J. Buffone, said the meeting did not yield any new information on the allegations being pursued by the ethics committee group. Califano declined to comment.

Attempts to get information on the Justice Department's investigation have been wholly unsuccessful, Buffone added.

"They won't even tell us if it's true" whether Dellums is being investigated by the Justice Department, Buffone said. Dellums' office said it had no further details on any of the allegations, either.

"We don't think it's anything to get worried about," Dellums aide Daniel Lindheim said last week.