Goblet of Fire

Harry finds out by watching the scene of a trial, in Dumbledore's Pensieve, why Neville is being raised by his grandmother. Frank was an Auror, and shortly after Lord Voldemort's disappearance was attacked and tortured by Barty Crouch Jr., Bellatrix Lestrange, Rodolphus Lestrange, and Rabastan Lestrange, who used the Cruciatus Curse on him and his wife, Alice, until they lost most of their mental faculties. The two of them are now residing at St. Mungo's.

Order of the Phoenix

At the celebration feast for Ron and Hermione becoming Prefects, Alastor Moody shows Harry a picture of the old Order. In that picture, we see Alice and Frank Longbottom smiling and waving.

Before Potions class one day, Draco Malfoy, taunting Harry, mentions something about people with mental infirmities being forced to stay at S. Mungo's. Neville, pushed beyond his endurance, tries to attack him, but is restrained by Harry and Ron. Ron and Hermione wonder what that was all about, but while Harry knows, he also cannot answer because of his promise to Dumbledore.

Just before Christmas, while Harry, Ron, Ginny, and Hermione are visiting Mr. Weasley at St. Mungo's, they run into Neville and his grandmother who are visiting Neville's parents.

When Neville is captured by Death Eaters in the Battle in the Ministry, Bellatrix Lestrange says she will torture him as she tortured his parents. She is stopped only by the arrival of members of the Order arriving.