Justice Department investigators have identified criminal wrongdoing in General Motors’ failure to disclose a defect tied to at least 104 deaths, and are negotiating what is expected to be a record penalty, according to people briefed on the inquiry.

A settlement could be reached as soon as this summer. The final number is still being negotiated, but it is expected to eclipse the $1.2 billion paid last year by Toyota for concealing unintended acceleration problems in its vehicles, said the people, who did not want to be identified because the negotiations weren’t complete.

G.M.’s eagerness to resolve the investigation — a strategy that sets it apart from Toyota, which fought prosecutors — is expected to earn it so-called cooperation credit, one of the people said. That credit could translate into a somewhat smaller penalty than if G.M. had declined to cooperate.

Former G.M. employees, some of whom were dismissed last year, are under investigation as well and could face criminal charges. Prosecutors and G.M. are also still negotiating what misconduct the company would admit to.