The autopsy reportedly found Law had a blood-alcohol level greater than 0.40 percent - five times the legal threshold for driving under the influence.
Medical experts say a blood-alcohol content of 0.35 percent or more can be fatal.
At a court hearing involving the release of Law's body for burial, her family said the woman, who grew up at the Jersey Shore, had a history of problems with alcohol and had been going through a difficult time after a breakup with another man.
"I begged them, I pleaded with them," Peruto said Wednesday night. "There is no evidence of criminality. Please do this while my father is alive." Peruto's father, legendary criminal defense lawyer A. Charles Peruto Sr., died Dec. 17 at age 86.
Peruto called on the District Attorney's Office to release the grand jury's findings, adding that the one-sentence announcement leaves him "under a cloud."
Peruto said investigators interviewed his alibi witnesses, and examined his and Law's cellphones and their text messages before her death, the cellphone towers used by their phones, the E-ZPass transponder from his car, and security videos from his apartment.
Peruto said he was considering an "abuse of process" lawsuit against Williams.
Williams' spokeswoman could not be reached for comment.
Beyond confirming the existence of the grand jury probe into Law's death after the explosion of news coverage last year, Williams has refused to comment on the matter, citing the secrecy of grand jury proceedings.
On May 25, Law was found facedown in a tub of water by a maintenance man entering Peruto's home. Peruto was visiting family at the Shore but raced home distraught over the death of the woman he called his "soul mate."
Although the Medical Examiner's Office has not publicly released an official cause of death, law enforcement officials at the time said they believed Law probably drowned in the tub, perhaps after a seizure. The body showed no sign of foul play or physical trauma.
For that reason, many were surprised when on June 7 Williams' office confirmed that an investigative grand jury would examine the circumstances of Law's death.
By July, Peruto was so angry that he wrote Williams calling for a "speedy conclusion" to the probe.
Beyond the emotional impact of Law's death and the public reaction to a grand jury probe, Peruto wrote that the rumors generated hurt his law practice and caused his bank to cancel his line of credit.