D. C. police continued their investigation yesterday into the death of a five-month-old girl who apparently drowned Monday in a bathub at the Capitol Hilton Hotel.

Police said the mother, visiting here from Sweden with her fiance, told them a man with a knife forced his way into her room at the hotel and threatened to drown the child unless the woman gave him money. After she told the intruder three times that she had no money to give him, the man placed the baby in the bathtub and drowned it, police said the woman told them.

Police said the woman, who speaks little English, called for help after the man ran away.

The woman, identified as Belet Melin, 29, and her fiance, identified as Lars Levin, 29, both of Stockholm, were interviewed extensively by police Monday and yesterday.

Police said Levin, a gem dealer, was not in the hotel at the time of the incident and had been visiting the Washington office of B'nai B'rith.

Yesterday, D.C. medical examiner James Luke said an autopsy on the child, Lilly-Sophie Levin-Melin, was incomplete, but that findings so far "are consistent with what we usually find in other drowning cases."

Homicide detectives have been hampered in their investigation by the woman's poor command of English. An interpreter from the Swedish embassy has been assigned to assist the police, and an attorney who represents the embassy, also has been sitting in on interviews with the couple.

Police said the medical examiner's office would release the child's body today to a local funeral home, which will arrange for the body to be returned to Sweden for burial.