Prosecutors said they were trying to negotiate a plea agreement Wednesday with a third suspect in Colombia's most notorious pyramid scheme after two executives accepted reduced sentences.

At least 700,000 Colombians invested as much as a half billion dollars in pyramid schemes that collapsed in November, authorities have said without providing exact figures.

Two associates of David Murcia, the jailed suspect accused of orchestrating the scheme, pleaded guilty to money laundering and on Tuesday received reduced prison sentences of 53 months each in exchange for cooperation.

The sentencing judge denied a request to allow the two — publicist Daniel Angel and legal adviser Margarita Pabon — to serve out the sentences under house arrest.

On Wednesday, two prosecutors visited a third suspect — William Suarez — in Bogota's La Picota prison to seek a plea deal, according to an official at the chief prosecutor's office, who spoke on the condition of anonymity because she was not authorized to discuss the case publicly.

Suarez — a brother-in-law of Murcia — is charged with money laundering, bribery and obtaining funds illegally.

A lawyer for Suarez could not be immediately reached for comment.

Angel and Pabon were both arrested on Nov. 18 as authorities moved to close down Murcia's company, DMG, which police have accused of laundering drug money.

Pyramid schemes typically offer dramatic returns by using money from a rapidly increasing pool of investors, eventually collapsing when the flow of new investment fails to cover everyone's promised returns.

DMG offered investors interest rates far above what banks offer, and allowed them to withdraw much of their deposits almost immediately in the form of electronics and other big-ticket items from warehouse-style stores.

Murcia was arrested in Panama in November and deported to Colombia.