Jones was reported missing by her father, Deandre Lane, Friday morning, The Detroit News reported. Lane told police he had been forced out of his car at gunpoint by two men who left with his car and the girl in the back seat.
Police and FBI officials said they were questioning Lane's story. Lane failed a polygraph test, the newspaper said.
"In the interest of allaying some of the fears of the public regarding the apparent randomness of Bianca's disappearance, the authenticity and credibility of the original version of events is under intense scrutiny by our investigative team," Police Chief Ralph Godbee.
Lane was being held on a traffic warrant.
Detroit police asked the public Sunday for help in the search.
"It is imperative that we continue to utilize every resource available to solve this investigation," police said in a statement asking for volunteers. "Therefore we are asking citizens to join law enforcement officers in the search for little Bianca."
April Johnson, 37, said she would not let the dreary Detroit weather stop her from joining the search party.
"Because I'm a mother, this story has touched my heart," Johnson said. "Ever since the story broke I've been holding out hope, but the days continue to go by."
About 65 volunteers gathered at Metropolitan United Methodist Church Monday morning to look for the missing girl.
"I had to come out because I'm the mother of a 19-month-old and if this happened to me, I would want everyone to support me," said Sade Franklin of Clinton Township.