LAFAYETTE, Colo. (AP) _ A letter from the maker of Dungeons & Dragons played a key role in getting police to reconsider their theory that the fantasy game influenced the murder- suicide of two boys last fall, a police chief says.

''I obviously felt they were telling me they would sue me if I didn't shut up. Any normal person would have thought that,'' Police Chief Larry Stallcup said Monday of the letter from TSR Inc. of Lake Geneva, Wis.

However, TSR spokesman Dieter Sturm said that while a letter was sent to Stallcup, ''no threats were made.''

Elsewhere, a Connecticut town's board of education will decide today whether to reconsider an earlier vote allowing children to play Dungeons & Dragons at school, although the board chairman says a policy change is unlikely.

A segment of CBS-TV's ''60 Minutes'' program Sunday dealt with suicides among teen-age players of Dungeons & Dragons players, focusing on the Nov. 2 deaths of brothers Daniel and Stephen Erwin, ages 16 and 12.

Stallcup said the ''60 Minutes'' piece gave the false impression that his department was covering up its findings to avoid litigation by TSR.

The initial police investigation theorized that the boys' fascination with the game played a major role in their deaths. ''There is no doubt that D&D cost them their lives,'' police Detective Greg Corrie said at the time.

But on Nov. 16, eight days after TSR wrote the chief and city attorney cautioning them about references to Dungeons & Dragons, that theory was publicly changed.

TSR Vice President Richard Koenings had asked for a written assurance that Stallcup's ''investigation and news releases will be fair and careful when making any reference to our products, products which have been endorsed throughout the world.''

Stallcup said police ''could not find any direct, concrete link'' between the game and the brothers' deaths.

He said direct involvement would have ''been a written statement from boys saying they did this because of the game. We did not find that.''

''60 Minutes'' excerpted a Nov. 20, 1984, letter from Stallcup to Pat Pulling, of Montpelier, Va., who founded a national organization after the suicide of her own son, also a Dungeons & Dragons player.

In the letter, Stallcup defended his department's conclusion that Dungeons & Dragons had ''no direct relation'' to the deaths, but added:

''I am sure you know a public servant is precluded from ever stating his or her personal beliefs. I sincerely hope you will understand what has happened and will forgive me. I do not feel very good about myself and I feel that I have lost a part of my integrity.''

At Putnam, Conn., members of the Christian Information Council last month asked the Board of Education to reconsider its decision to allow students to play the game during activity periods. The fundamentalist group said it encourages young people to accept suicide and teaches a religion of the occult.

Proponents of Dungeons & Dragons say the role-playing game game allows a child to use his imagination and develops math skills.

The board voted unanimously in July to allow the game to be played during activity periods, provided a child has permission from a parent.

''The board has made its decision. I don't see anything more happening with this,'' board chairman Joseph Pempek said Sunday.