So said Danielle Le Guennec, 68, explaining how she and her husband came to possess a box full of 271 previously unknown sketches, paintings and collages by one of the 20th century’s most celebrated artists.

“It was very straightforward,” she said in a telephone interview on Monday, after the French newspaper Libération reported the find. Her husband, Pierre Le Guennec, 71, had worked as an electrician in three of Picasso’s homes on the French Riviera in the early 1970s. “My husband was getting ready to leave” one day, she recounted, and without much ado or any explanation, Picasso gave him “a box.”

Picasso, she added, “never explained anything.”

In September the couple boarded a Paris-bound train with a suitcase full of works, including several watercolors, dozens of lithographs, more than 200 sketches and 9 Cubist collages, in the hopes of having it authenticated by Claude Ruiz-Picasso, the artist’s son and the administrator of the Picasso estate.

Suspecting that the works were stolen, Mr. Ruiz-Picasso contacted a lawyer, who filed a lawsuit on Sept. 23 claiming that the works were “stolen goods”; investigators seized the art from the Guennecs’ home in the South of France two weeks later. The inquiry is continuing, and it is unclear what will become of the artworks.

The cache, which appears to date from the first three decades of the 20th century, has been valued at about $80 million, according to Jean-Jacques Neuer, the lawyer representing Mr. Ruiz-Picasso; four other heirs; and Picasso’s stepdaughter, Catherine Hutin-Blay.

“We’ve never seen anything like this with regard to Picasso,” Mr. Neuer said in a telephone interview. “It’s completely stupefying.” He added: “There is no debate over the authenticity of the works. There is no possible doubt.”

Picasso was known as an inveterate collector of the artifacts and detritus of day-to-day life, and held particularly tightly to his artworks; his heirs say they doubt he could ever bear to part with such a sizable collection.

“He kept everything: letters, Métro tickets, tickets for the theater or bullfights,” Mr. Ruiz-Picasso told Libération. He said many of the 271 pieces were undated.

“He always dated, signed and dedicated his gifts,” Mr. Ruiz-Picasso said. “I leave it to the justice system to shed light on the matter. We ourselves are certainly not acting for our own profit. We’re not in need.”

Beyond the question of how the Guennecs obtained the works, it remains unclear how it was possible for the art to have gone unrecorded in the first place.

Unknown works by Picasso have surfaced here and there in the past, said Christine Pinault, an official at the Picasso Administration, the organization that manages the Picasso estate. The artist produced nearly 40,000 works in his lifetime, and offered many to friends and admirers. But never has such a concentration come to light.

“There are only questions in this whole story, for the moment,” Ms. Pinault said. “Everyone is wondering how such a thing could happen.” She viewed the collection in September.

Ms. Le Guennec said the box of Picassos had sat in the garage of her home for 30 years. But Mr. Le Guennec recently underwent major surgery, and they began to worry about their children’s inheritance, she said. And the box came out so she could authenticate its contents.

“We don’t have anything left now,” she said, but added, “We have our lawyer.”