OAKLAND (CBS SF) — A 33-year-old Oakland man has been charged with the special circumstances murder of his missing 71-year-old grandmother who was last seen at her home on July 6th, Oakland police announced Monday.

Maurice Washington Jr. was being held without bail in Alameda County jail after he was charged with first-degree murder with special circumstances for allegedly killing Theola Polk for financial gain.

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Maurice Washington, Theola Polk (Oakland Police Dept.)

Polk had been the subject of an extensive search after she went missing. The search included areas close to her residence, as well as railroad tracks and landfills. At times, cadaver dogs were also used as a resource during some of the search areas.

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“As a result of this in-depth investigation, including interviews of witnesses and evidence collected, investigators focused their investigation on Washington, who is Polk’s grandson,” Oakland police said in a news release.

Washington was initially arrested on July 14 on an unrelated charge. After interviews with investigators, he was additionally arrested on July 17 for the murder of Polk.

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The 71-year-old’s body has yet to be found.