Two Congressional committees are probing alleged official U.S. collusion in the death of an American in Chile following the 1973 military coup.

Spencer Davis, spokesman for the Senate Intelligence Committee, said this week that the panel was engaged in an "active investigation" of the death of Charles Horman, whose gunning down in the after math of the coup that overthrow Chilean President Salvador Allende has never been solved.

A House International Relations subcommittee is also investigating the case and there are indications that the committee is seeking to bring a former Chilean official to Washington to testify.

The former official, Rafeal A. Gonzalez Verdugo, took refuge in the Italian embassy in Santiago last year and declared that he was present when a Chilean general ordered the killing of Horman, a free-lance writer from New York who was a supporter of the fallen leftist government.

Verdugo also said that a man he took to be a U.S. Intelligence officer was present. The State Department later interviewed Verdugo but he said that Chile refuses to assure him safe passage out of the country for possible testimony here.

R. Michael Finley of the House subcommittee staff said the group was requested classified information that the State Department so far has failed to produce. "We consider the case open . . . If someone is reponsible, he should be punished," he said.

In another development, Horman's family filed suit in Federal District Court here Thursday for $4.5 million in damages from former Secretary of State Henry Kissinger and 10 other U.S. officials at the time.

Representing Horman's widow and parents are lawyers Peter Weiss of the Center for Constitutional Rights in New York and Ira Lowe of Washington. Their 36-page complaint charges that Kissinger, Nathaniel Davis, former ambassador to Chile, and nine other officials by "acts and ommissions" contributed to Horman's death.

The Center for Constitutional Rights, which is financing the suit, has taken an active role in civil liberties cases and was particularly involved in Vietnam war litigation.

Horman's father, Edmund, a semi-retired businessman, has spent much his time in the last four years gathering information - amplified by numerous filings under the Freedom of Information Act - on the mysterious killing.

Charles Horman, 31, was arrested on Sept. 17, 1973, by what witnesses say was a military patrol, and found buried in a niche of the Santiago national cemetery on Oct. 18. Chilean authority have denied making the arrest or any knowledge of how he died.

Throughout the month after Horman's disappearance, U.S. officials disclaimed any information on his whereabouts.

An autopsy later put the probably date of death as Sept. 20 and said it was caused by gunshot wounds. It later was established that the embassy had received a reliable support of Horman's death about the end ofSeptember.