Lyndon Larouche's followers have won unexpected victories in primaries this year, and may win more: their candidates won the Democratic nominations for lieutenant governor and secretary of state in Illinois, and a LaRouche follower is the only Democrat running for the party's nomination in the 40th district of California.

But LaRouchites have also been busy responding to investigations of their fundraising and other activities, as detailed by the Post's John Mintz, and in the long run these may have more to say about the movement than their electoral successes this spring. A federal grand jury in Boston is probing what prosecutors call "a massive pattern of credit card fraud" by the 1984 LaRouche presidential campaign. The Federal Election Commission is investigating a number of complaints of fund improprieties. The Justice Department is investigating possible tax fraud by LaRouche followers and one LaRouche-related corporation. State law enforcement agencies, including Maryland securities officials, are investigating LaRouche activities by LaRouche corporations.

None of these investigations has been completed, and none has resulted in criminal charges. You might reasonably ask why investigations of charges made about activities that took place in 1984 or earlier have reached no conclusion. One answer appears to be that the targets of these investigations have used every legal opportunity to slow them down and have in some cases failed to produce documents called for by the courts. And because there are many LaRouche organizations, it is hard to pin down responsibility; courts in Massachusetts and New Jersey have levied hefty fines for failure to respond to court orders, but it is not clear that the particular defendants have anything like the assets to pay those fines if they are upheld on appeal.

Any citizen is entitled to use all his legal rights to oppose a government investigation, and as a general rule prosecutors should hesitate to interfere with the conduct of political campaigns. But the number and nature of the complaints against LaRouche organizations and individuals make it plain that the prosecutors and the FEC have a responsibility to act, and there is no reason to believe Mr. LaRouche's wild retaliatory charges against the FBI and the Justice Department.

These cases ought to be resolved before the 1988 campaign, in which Mr. LaRouche says he will again be a candidate for the Democratic presidential nomination. No doubt voters will reject LaRouche candidates in elections: there is little demand in the political marketplace for the commodity they supply. The political process will do its work. The legal process necessarily works more slowly and deliberately. The prosecutors and the FEC have more hard work and abuse ahead of them, but they must continue all the investigations -- despite the tactics they face -- with a view to bringing prosecutions wherever the evidence warrants.