LONDON — The cartoonist known as Luz, who drew the polarizing cover of a weeping Prophet Muhammad for the first issue of Charlie Hebdo after the January attack on its office in Paris, is leaving the satirical French newspaper, saying the pressure had become “too much to bear.”

In an interview with the newspaper Libération published on Monday, the cartoonist, Renald Luzier, said he could no longer face the trauma of working without the colleagues who were killed in the attack.

“Each issue is torture, because the others are gone,” Mr. Luzier said. “Spending sleepless nights summoning the dead, wondering what Charb, Cabu, Honoré, Tignous would have done is exhausting,” he added, referring to cartoonists who were killed by two Islamist brothers by their pseudonyms.

Mr. Luzier, who will leave in September, was among a group of dissidents at the publication who wrote an editorial in the French daily Le Monde this year questioning its direction.