Former Comverse Technology Inc. Chief Executive Jacob “Kobi” Alexander has been arrested in Namibia after being charged last month in an alleged scheme to improperly backdate options at the company from 1998 until earlier this year, prosecutors and law enforcement officials confirmed Wednesday.

In a press release, the U.S. Attorney’s office in Brooklyn and the FBI also announced the unsealing of a 32-count indictment that charges Mr. Alexander with conspiracy, securities fraud, making false filings with the Securities and Exchange Commission, mail fraud and wire fraud. He faces up to 25 years in prison on the most serious charge of securities fraud.

Mr. Alexander was arrested earlier Wednesday in Windhoek, Namibia, pursuant to a provisional warrant issued by a Namibian court at the request of the American government, prosecutors said.

America intends to seek his extradition, and he is expected to appear before a court in Namibia within 48 hours, they said.

A lawyer for Mr. Alexander didn’t immediately return a phone call seeking comment Wednesday.

Mr. Alexander, along with two other former Comverse executives, was originally charged in a criminal complaint issued in August with conspiracy to commit mail fraud, securities fraud and wire fraud.

The SEC has separately filed civil charges against the men.

According to the newly unsealed indictment, prosecutors have alleged that Mr. Alexander and the two other executives engaged in a scheme to backdate millions of stock options for themselves and other employees when the stock was trading at periodic lows. As a result, Mr. Alexander “reaped substantial personal gain” from his alleged conduct.

The government also has alleged that Mr. Alexander and others used fictitious names to generate hundreds of thousands of backdated options, which were parked in a “secret slush fund” designed to evade the requirements of Comverse’s stock-option plans. Mr. Alexander then unilaterally awarded options from the slush fund to favored employees, according to the indictment.

The slush fund was first named I.M. Fanton, after “Phantom of the Opera,” according to the indictment. An earlier complaint said the assistant who helped manage the slush fund named after “Phantom,” saying that the name fit what they were being asked to do: create phantom employees.

The slush fund’s name was later changed “Fargo” — based on the Coen brothers movie of the same name, according to the indictment. An earlier complaint said the name was changed after thinking better of the wisdom of naming it after “Phantom.”

Prosecutors are seeking the forfeiture of about $138 million in Mr. Alexander’s assets.

In a civil action filed earlier this year, the government said Mr. Alexander allegedly used accounts in his name at Citibank to launder proceeds of the fraud by wiring $57 million to Israel in July in an attempt to conceal the proceeds from American authorities.