A Dorchester County woman whose three children were killed in a 1989 house fire set by a former boyfriend has filed an $18 million civil suit against the Cambridge city government and a police officer for allegedly failing to protect her and her family from "a foreseeable chain of events" that led to the arson and deaths.

In the suit filed Monday in U.S. District Court in Baltimore, Carol L. Pinder claims that Cambridge police should have jailed Don Pittman, Ms. Pinder's former boyfriend, after he broke into her Pine Street home, attacked her and threatened her life on March 10, 1989.

Instead, according to the suit, police charged Pittman with two minor crimes and released him on his own recognizance.

Pittman later returned to the house and set it afire, killing Ms. Pinder's three children, Kim, 11, LaToya, 4, and Troy, 2. The suit states that Ms. Pinder, having been reassured by police that Pittman would pose no danger to the family, had returned to her job at an Easton factory.

Pittman pleaded guilty to three counts of murder stemming from the 1989 arson and was sentenced to life in prison without parole.

The suit also claims that police should have treated Pittman's assault on Ms. Pinder more seriously because they were aware that less than a year earlier Pittman had set fire to the Pinder residence. He was convicted of arson and and sentenced to 18 months in prison, with a year of the term suspended.

Barbara Gold, Ms. Pinder's lawyer, said yesterday that she and her client filed the civil suit against the Cambridge city government and Pfc. Donald Johnson, the officer who responded to the 1989 break-in, only because Cambridge officials refused to commemorate the deaths by establishing a park and a scholarship.