[2] In 1940, returning to Beirut, he co-published with Fouad Hobeiche the periodical Al Musawwara ("The Illustrated"), chronicling World War II events in articles and photos, an innovation in the Lebanese press.

Inspired by the reduced number of letter shapes found on Arabic typewriters, Mrowa suggested to adopt similar principles for professional typesetting.

Walter Tracy, at the time L&M's typographical adviser, reviewed Mrowa's proposal and agreed to pursue it despite concerns of the mother company Mergenthaler Linotype.

In the ensuing collaboration, Mrowa, Al-Hayat's lettering artist Nabih Jaroudi, and L&M staff under the guidance of Walter Tracy developed a new Arabic printing type.

The motive was never conclusively established, but investigators eventually linked the killing to the Independent Nasserite Movement or INM (Leader: Ibrahim Kulaylat, commonly known as "Al-Murabitoun" in Arabic "المرابطون") who considered Mrowa's vocal criticism of the Arab nationalist movement (then led by Egyptian President Gamal Abdel Nasser) as a threat.

Upon his death, his widow Salma El-Bissar took over the two newspapers, running them until the outbreak of the Lebanese Civil War forced the suspension of publications.

In 1988, Mrowa's son Jamil reestablished Al-Hayat with his partner Adel Bishtawi, and sold it the same year to Saudi Prince Khalid bin Sultan.