Leslie Carter, 25-year-old sister of the Backstreet Boys’ Nick Carter and pop star Aaron Carter, died of an overdose, according to reports.

Three drugs — Olanzapine, used to treat symptoms of bipolar disorder, a muscle relaxer and anti-anxiety drug Xanax — were found near Carter’s body, according to a police report posted on the Internet yesterday by ABCNews.com.

Stepmother Ginger Carter told cops Leslie had “a long history of mental illness and was on medication for her depression.”

Ginger called 911 when Leslie was discovered in bed not breathing on Tuesday afternoon.

Carter, who was also a singer and appeared with her brothers on the family’s 2006 reality show, “House of Carters,” was the mother of a 10-month-old daughter.

An official ruling on the cause of death will not be made for several weeks, pending the outcome of toxicology tests.

So far the family has refused to provide details about the death. But Nick is set to appear today on “Good Morning America.’’