Speaking at an event at the British Parliament, Marina Litvinenko said her husband's murder — and "the example of the Russian president" — may have contributed to an environment in which governments think "it's just so easy to kill people" without provoking a strong response.
Alexander Litvinenko, a Russian agent turned Kremlin critic, died in November 2006 after drinking tea laced with polonium-210 at a London hotel. A public inquiry concluded that he had been murdered by Russian intelligence, likely with the approval of President Vladimir Putin.
Britain has named two suspects, who remain free in Russia. Marina Litvinenko said the death of Khashoggi and the poisoning of ex-Russian spy Sergei Skripal in England earlier this year were evidence that her husband's death had not deterred governments from seeking to silence their critics.
Khashoggi, who had criticized Saudi Arabia's assertive crown prince, has not been seen since he entered the Saudi consulate in Istanbul earlier this month. Turkish authorities say he was killed there in a pre-planned murder.
Litvinenko said Western governments did not respond strongly enough after her husband died. She said that with Western nations considering what action to take against Saudi Arabia, "it's maybe a good point to see if something might change."
"It's very important to react (to) any kind of behavior and crime," she said. "Because if you will make nothing happen today, you will just be not sure what might happen tomorrow."