INDIANAPOLIS -- Three Indianapolis Metropolitan Police officers accused of running a marijuana distribution ring resigned from the department Thursday evening.

A statement released by IMPD said the three submitted their handwritten resignations in jail after being served with notices that the chief was moving to fire them.

Federal investigators said James D. Davis, 33, Robert B. Long, 34, and Jason P. Edwards, 37, used their jobs as police officers to divert marijuana and the cash from illegal drug sales for their own use.

Their resignations were effective immediately.

All three officers remained in federal custody pending a detention hearing scheduled for Monday. Federal court documents did not list any attorneys representing the officers.

The three were indicted on charges of conspiracy to possess with intent to distribute more than 50 kilograms of marijuana, and possession and attempted possession of marijuana with intent to distribute. They also face firearms charges. The indictment was unsealed Tuesday, the day following their arrest by the FBI.

The officers were arrested Monday after an investigation that started in March and involved undercover work, surveillance of the officers and phone call monitoring.

The indictment referred to Long, a narcotics detective, as the conspiracy's leader.

It said that in April he seized a parcel containing up to 13 pounds of marijuana from the FedEx hub at Indianapolis International Airport. About eight pounds were removed and sold for $4,000. Long then allegedly turned in nearly five pounds from the parcel to a police narcotics vault to cover up the missing portion.

Authorities also allege that Long used a fake search warrant to get a key that let him and Davis search an apartment for marijuana and that the three also took five pounds of marijuana and $18,300 hidden in the closet of a vacant home earlier this month.

A fourth man who allegedly sold the marijuana for the officers was indicted on a conspiracy charge.

Each could receive a maximum of 20 years in prison and a $1 million fine if convicted.