KISS star Gene Simmons believes a series of “bad decisions” led to the death of former KISS guitarist Ace Frehley.

In an interview with the New York Post, the rocker suggested that substance abuse contributed to Frehley’s fatal fall down the stairs in his New Jersey home studio.

The founding KISS member died of blunt-trauma injuries to his head due to the fall, the Morris County Medical Examiner confirmed in a report obtained by PEOPLE on November 10.

“He refused [advice] from people that cared about him — including yours truly — to try to change his lifestyle. In and out of bad decisions. Falling down the stairs — I’m not a doctor — doesn’t kill you. There may have been other issues, and it breaks my heart,” Simmons told the New York Post.

“The saddest thing — you reap what you shall sow, unfortunately,” the bassist added.

According to the Post, a separate toxicology report on Frehley’s blood at the time of his death will be issued.

“It breaks my heart,” Simmons continued, before describing Frehley’s private funeral service that was held on October 22.

“Peter Criss, our founding drummer, Paul [Stanley] and myself went to the funeral, open casket,” Simmons recalled.

“It was just heartbreaking. Saddest of all perhaps is that Ace just couldn’t stay alive long enough to sit there proudly at the Kennedy Center and listen to — I can’t even tell you who’s going to come out … really impressive people, just to say how much KISS meant to them,” he added, referring to President Donald Trump’s upcoming honors for the legendary rock band at the Kennedy Center.

“What can you say — sad,” Gene Simmons concluded.