The District of Columbia police chief said a search of a park for a missing 8-year-old girl is a "recovery operation," although police haven't given up hope of finding the child alive.

Chief Cathy Lanier said Relisha Tenau Rudd has not been seen since March 1. Police are looking for 51-year-old Kahlil Malik Tatum, a murder suspect and a janitor at a homeless shelter where Relisha lived. 

Authorities spent Thursday searching for the missing girl at Kenilworth Park and Aquatic Gardens in the northaest section of Washington, D.C., Fox affiliate WTTG reported. No evidence had been located by the time the search was called off Thursday evening.

An Amber Alert was issued for Relisha last week. According to Lanier, Relisha was last seen on March 1 with Tatum, the man police believe abducted her. Lanier said that is the last time they can confirm Relisha was seen alive.

On March 2, Lanier said Tatum purchased a carton of 43-gallon self-tying black trash bags, and later was in the area of the aquatic gardens in Kenilworth Park for a period of time. After that, Lanier said Tatum was going to work and was seen in the city through March 20, but there were no sightings of Relisha, according to the station.

Lanier said based on this information, the search for Relisha in the park is a recovery operation. But she said authorities are not ruling anything out until the girl is found.

"We have not given up hope that we may still find Relisha alive," Lanier said.

After Tatum's wife was found dead in a Maryland motel room on March 20, there have been no confirmed sightings of him. Billboards in the Atlanta area are plastered with images of Tatum. 

On Thursday, an FBI spokesman confirmed the agency was assisting in the search, according to the station.

Tatum is charged with killing his wife, 51-year-old Andrea Tatum, whose body was found inside a motel room in Oxon Hill, Md. Officers found her body while they were searching for Relisha. A warrant was issued for his arrest, and he is charged with first-degree murder and unlawful flight to avoid prosecution.

Tatum was added to the FBI's "Most Wanted List" on Wednesday. The FBI also released video to the public on Tuesday showing Tatum and Relisha walking down the hallway of a northeast D.C. hotel on February 26.

A total reward of $70,000 is currently being offered for information leading to Tatum's arrest and conviction, and for locating Relisha. The FBI offered a reward of up to $25,000 for Relisha's location and return, and a separate reward of up to $20,000 for information leading to Tatum's arrest. The Prince George's County Police Department has also offered a reward of up to $25,000 for information leading to Tatum's arrest and indictment.

Anyone with knowledge of Tatum's whereabouts is urged to call 911 immediately or the FBI at 1-800-CALL-FBI.

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