Attorney-General Avichai Mandelblit announced Monday that a police probe into the “Submarine Affair” has developed into a full-blown criminal investigation.The affair concerns allegations that Prime Minister Benjamin Netanyahu’s personal lawyer, David Shimron, lobbied defense officials on behalf of German shipbuilder ThyssenKrupp for a multibillion-shekel submarine sale.The prime minister is not a suspect in the investigation.Questions over the 2014 submarine deal surfaced in November with a Channel 10 report that Shimron worked for the Israeli representative of ThyssenKrupp and pushed to buy submarines from the firm over the objections of the defense establishment, including then-defense minister Moshe Ya’alon. Ya’alon has reportedly given testimony in the case. Mandelblit soon opened an initial probe of the allegations.A statement from the Justice Ministry said the decision to upgrade the investigation from probe to criminal investigation was based on information gathered by the police in recent months and evidence that raises a reasonable suspicion, “that some of those involved in the affair committed crimes of public corruption.”A police spokeswoman for Intelligence and Investigations Division told The Jerusalem Post that this investigative material had “accumulated” leading to attorney-general’s decision to upgrade the investigation.Channel 10 reported earlier this month that recent testimony to police from former OC Israel Navy Adm. Ram Rothberg has allegedly substantiated suspicions leading to the criminal investigation. In July 2014, the Defense Ministry issued tenders for the ship purchases after negotiations to buy from Germany fell through.A few months later, the navy requested that the tender be frozen, after Germany signaled its renewed willingness to reach a deal with Israel. A month later, the Defense Ministry froze the tender, and the two countries signed a memorandum of understanding on the purchase of the ships in December 2014.ThyssenKrupp, which sold the Israel Navy its newest Dolphin- class submarines, has been accused of bribing officials around the world to promote sales of its submarines. According to the German financial newspaper Handelsblatt, ThyssenKrupp opened an internal investigation into suspicions that employees of its Marine Force International subsidiary had bribed officials in Greece, Turkey, South Korea, Pakistan and Indonesia.Miki Ganor, ThyssenKrupp’s representative in Israel; and former Israel Navy commander Adm. Eliezer Marom will be questioned under caution in the investigation, according to the Channel 10 report earlier this month.Ya’alon reportedly testified to police investigators against the prime minister in the affair.Ya’alon reportedly offered the police details about the contacts Netanyahu held with German officials regarding the acquisition of three submarines and several other warships, which happened without the knowledge of the security establishment.Israel has three Dolphin-class submarines and two Dolphin 2-class submarines. Another one is expected to be delivered in 2018. The Dolphin 2-class submarines are expected to replace the older Dolphins at a combined cost of NIS 5 billion ($1.3b.) Yonah Jeremy Bob, Gil Hoffman and Anna Ahronheim contributed to this report.