There were no suspects in the case and no known motive for the killing, they said.

Neither of the killings in which he was a suspect involved robbery or any other known motive, the authorities said.

There was no known motive for the attacks.

The police said they had no suspects, no witnesses and no known motive.

There wasn't much evidence, period; no witnesses and no known motive.

The gunman remained at large last night, the police said, and there was no known motive for the shooting.

The suspect has no known motive, but perhaps she's a pathological killer.

There is no known motive for the apparent suicide.

To satisfy you: partly the absence of a known motive for him, but mostly what he said and did in this room Tuesday afternoon.

And, investigators said, no known motive for murder.