"The reality of it is, that you can protect someone from everything, but you cannot protect them from themselves," Jacobs said.
Jacobs said that though he was shocked and saddened, he was not totally surprised when Houston died. He also said that he had warned her and husband Bobby Brown it would happen, and decided to quit his job when she did not stop abusing drugs.
"I said, 'you hired me to do a job, to protect you … but I cannot protect you from yourselves.' I took a stand and it was about four months later that we decided to part company," he said.
According to Jacobs, after he left, Houston turned over security to her relatives. Her head bodyguard until her death was brother-in-law Billy Watson.
"It would seem that a closer eye might have been kept," Jacobs said. "But there again there's an old saying that the boss may not always be right, but the boss is always the boss."
ABC News' Eileen Murphy contributed to this report.