A 49-year-old man has been arrested in connection with the killing of Alexandria community activist, Lenwood “Lenny” Harris, whose body was found last week in a Fort Washington well, police said Tuesday.

Linwood Johnson, of Oxon Hill, was charged with first-degree murder, police said. Authorities said they are seeking more suspects and expect there will be additional arrests soon.

During a Tuesday press conference, police revealed few details about what led to the killing but said they think robbery was the motive. They said Harris, 53, knew the suspects but would not elaborate.

Assistant Chief Kevin Davis said Johnson provided a “full, written and verbal confession.” He also said police believe they have recovered a murder weapon.

Harris was last seen Sept. 21 at the Charles Houston Recreation Center in Alexandria. Hours after he disappeared, a tattooed man was caught on an ATM surveillance camera using Harris’s bank card. Police also found Harris’s cellphone on the Woodrow Wilson Bridge.

Homicide detectives believe he was shot and killed soon after he went missing, authorities have said.

But Harris’s body went undiscovered for months until last week, when police said an anonymous 911 caller reported that a body had been dumped down the well on a vacant property in the 11900 block of Old Fort Road, police said.

Harris, who had lived with his wife in Del Ray, was well known for popping in on Alexandria City Council meetings. He made an unsuccessful run for the council in 2007 and co-founded the nonprofit Operation H.O.P.E., which offers mentoring and career development services.

(The Root D.C.: Remembering Lenny Harris)