CHRIS ROCK ABANDONS HIS ADOPTED DAUGHTER, AFTER DIVORCE FROM WIFE?

Chris Rock has not seen the 7-year-old girl who lived with him since she was an infant in more than a year ... and we're told it's because he believes his estranged wife Malaak did something shady to get her here in the first place.

It's a bizarre story ... and one that triggered an international investigation. Here's what we know. Back in 2008, a 6-month-old named Ntombi from South Africa began living with the Rock family. The girl stayed in the family house ever since. Ntombi was even enrolled in a New Jersey school.

Ntombi's biological parents reportedly were unemployed South Africans and somehow the kid ended up at the Rock home.

Everything changed last year when Chris and Malaak began divorce proceedings. We're told Chris maintained his relationship with his 2 biological daughters but hasn't seen Ntombi since the split.

Around the same time as divorce docs were filed, South African officials opened an investigation to determine how the child went from their country to the U.S., when there was no evidence of a legal adoption.

As for why he went radio silent with Ntombi ... sources connected to Chris say he never signed legal docs to adopt her, and bringing her over to the U.S. was all Malaak's doing.

As far as we can tell there was never an adoption. It's unclear how and why the biological parents allowed Ntombi to live with the Rock family for years.

Chris' rep tells TMZ he does not have an adopted child. We tried reaching Malaak's lawyer, but did not get a return call.