Police say that calling off an Amber Alert called in the search for a missing ten-month-old Kansas City, Mo., infant was a formality, as the alerts function to raise awarness of a missing child at the beginning of the investigation.

Although the investigation and search for Lisa Irwin continue, an active Amber Alert is no longer necessary in this case, CNN reports a police spokesperson saying.

According to reports from ABC News and The Kansas City Star, police do not have any significant leads on the second day Lisa Irwin has been missing.

Neither of her parents -- who live together but are unmarried -- are considered a suspect, and both have been cooperative with the investigation.

On Wednesday, Jeremy Irwin and Deborah Bradley pleaded for their daughter's safe return during a press conference at a police command center near their home.

Please drop her off anywhere, Jeremy Irwin is quoted as saying by The Associated Press.

We just want our baby back, Deborah Bradley said, while clutching a Barney doll that presumably belonged to Lisa.

Police and the FBI have worked together in an exhaustive search for Lisa Irwin, performing an intense search of Irwin's home and the surrounding area, and interviewing neighbors and acquaintances of the family.

Kansas City police Capt. Steve Young told ABC's Good Morning America Wednesday that police are not ruling out any possibilities  -- including the involvement of Lisa's parents -- but that neither her mother or father were a suspect and that both had been fully cooperative with the investigation.

Detectives are looking at every possible angle, Young told MSNBC. All we know is that there should've been a 10-month-old in that house and we are doing everything we can to find the kid...We've received several tips and we certainly encourage people to call, but we also need information that is specific to the case, 

According to Lisa's parents, she was last seen at around 10 p.m. Monday night when her mother put her to sleep, and her father noticed she was missing when he returned home from work at around 4 a.m.

Police intially suspected an intruder but have not yet determined the location of a forced entry. There was no information as to whether the child's room included an operative baby monitor, Sgt. Stacey Graves told the Kansas City Star.

One neighbor interviewed said he had seen a man carrying a baby near the Irwin's home at 2 a.m. Tuesday, but police spokesman Darin Snapp told MSNBC that lead went nowhere.

Two other children, sons from Lisa's parents' previous relationships, live in the home. Both are boys aged ten or younger.

Lisa Irwin has blue eyes and blond hair. She is 30 inches tall and weighs 26 to 30 pounds. The baby was last seen wearing purple shorts and a purple shirt with white kittens on it. She has a cold with a cough, a small bug bite under her left ear, a beauty mark on her outer right thigh, and two bottom teeth.

Police are urging people with any possible information that could lead to Lisa's whereabout to call TIPS Hotline at 816-474-8477, or 911.