JERUSALEM — Prime Minister Benjamin Netanyahu is not a suspect in the so-called submarine affair, one of the corruption scandals rocking Israel. But with his personal lawyer, the man he appointed as national security adviser, and now his former chief of staff among the expanding parade of suspects, analysts and critics assert that if Mr. Netanyahu did not know what was going on, he should have.

David Sharan, who was Mr. Netanyahu’s chief of staff from late 2014 to 2016, was arrested on Sunday in connection with the case, along with a former Navy chief and a former commander of the elite naval commandos. On Monday a former legislator and minister and an adviser to the current minister of energy were also arrested.

The investigation involves lucrative contracts with a German shipping company for the purchase of submarines and new missile ships that Mr. Netanyahu championed. Often described here as the gravest corruption case in Israel’s history, it began with a monthslong police inquiry and turned into a full-blown criminal investigation in February.

Public interest in the case has been intense. Apart from concern that corruption has taken root on the watch of an entrenched political leadership, many worry about its bearing on national security and the integrity of the military, Israel’s most hallowed institution.