When was the Jack The Ripper case closed?

Nope still a open case.

Actually, the case was officially closed in 1892.

//The case of Jack The Ripper is unresolved and officially considered an open case. As with any open criminal investigation the files are not accessable to the public. British law dictates that the unsolved Ripper crimes, although still an open case, after 75 years the files are opened. This ensures that more than likely the killer is long dead, as would be any family members of the victims that could suffer from such information being scutinized by the public.