(CNN) -- A mystery surrounding the disappearance of a Washington girl intensified on Thursday as police searched a local park as part of an investigation centered on a man who may be with her and is now wanted for his wife's murder.
"We're not making any assumptions, but I think it'd be prudent for us at this time to make sure we've searched - and this is a very large area - searched this area very well," said D.C. Police Chief Cathy Lanier. "We cannot ignore the possibility that he may have killed her."
The search of the aquatic gardens area of Kenilworth Park was prompted by evidence the man, identified as Kahlil Malik Tatum, 51, spent time there after the last credible sighting of Relisha Tenau Rudd, 8, on March 1.
"On March 2, we know that Mr. Tatum purchased, among other items, a carton of black, 42 gallon, self-tie contractor trash bags within the District of Columbia," Lanier said at a news conference near the search area. "Not long after that purchase, Mr. Tatum was in the area of the aquatic gardens for a period of time."
Lanier said after the last sighting of Rudd, Tatum continued to go to work and was seen around D.C. several times between March 2 and March 20. Lanier said Rudd was not with Tatum in any of those sightings.
Tatum, who was reportedly a janitor at the shelter where Rudd and her family had been staying, appears to have had permission to be with Rudd. The FBI says law enforcement believes Rudd could be with Tatum.
The FBI has released surveillance footage of the two together from February 26. The video purportedly shows them walking down a hallway of the Holiday Inn Express located in Washington.
The FBI has also released multiple photos of Tatum and Rudd.
Rudd's disappearance took on new urgency when police discovered the body of Tatum's wife, Andrea Denise Tatum, 51, at a suburban Maryland motel last week. He has not been seen since March 20.
Police in Prince George's County have since issued a warrant for Tatum's arrest in his wife's slaying and Washington authorities issued an Amber Alert for Rudd.
Rudd is described as an African-American female, 4 feet tall, weighing approximately 70 to 80 pounds, with black hair and brown eyes. An FBI reward in the case was increased from $25,000 to $70,000.
According to the FBI, Tatum is 5-foort-7 and weighs around 170 pounds. He's an African American with a "distinctive tattoo on his left upper arm."
"While this current operation in the aquatic gardens would be best described as a recovery operation, we have not given up on hope, given up hope that we will still find Relisha alive," Lanier said.