motive for a crime
motive of a crime

And when there's zero motive for a crime, you're still left with the question - why?

"There must always be a motive for a crime like that," said Harriet.

Instead of a "mind-policing-approach" we would support a hate-crime-legislation approach that considers racist and xenophobic motives for a crime an aggravating circumstance and increases sanctions on these crimes.

To the Editor: An Oct. 28 letter about hate-crimes legislation states, "There is no precedent in our legal system to increase the harshness of a sentence based on the motive for a crime."

In addition, the Wet terroristische misdrijven ("terrorist crimes law", in effect since 10 August 2004), also states that, if there is a terrorist motive for a crime, the term can be increased by half.

Where in a mystery the motive for a crime such as insurance fraud can be greed, in a thriller mere money doesn't come across as believable for all the terrible things the antagonist will do.

Some Senate Republicans criticized the proposal, saying that it would require the authorities to try to ascertain the psychological motive for a crime and that there was no evidence that offenses against the specified groups were not being prosecuted now.

And there has been many a time when, because of close contacts with police officers, reporters have been able to scotch local theories about the motive of a crime which might otherwise have been reported.