The weeklong mystery surrounding the disappearance of a 10-year-old Crystal boy deepened Tuesday when police said they don't believe the boy's father is telling them everything he knows about the case.

Barway Collins' father, Pierre Collins, flunked a lie-detector test and may have lied to police about details of his son's disappearance, Crystal Police Chief Stephanie Revering said at an afternoon news conference.

Collins has not been arrested or charged, but is considered a suspect in the boy's disappearance, she said. She declined to talk about what role police believe he might have played.

Police also want to talk to the boy's uncle, Revering said, adding that they are not sure if he is a biological uncle or if "uncle" means close friend. Pierre Collins has not provided the uncle's name, Revering said.

The father and uncle are believed to have been the last two people with the boy before he disappeared, police said. Revering showed a school van video in which Barway tells a friend that he sees his father, then his uncle, as he is let out of the van in front of his apartment building in the 5400 block of Douglas Drive N.

The boy was last seen after school last Wednesday, walking away from the entrance to the apartment building. An entryway video recorded that moment, as well as the brief appearance of two adults police have said they want to talk to.

The school van video released Tuesday was taken just before those moments.

Police said Barway's biological mother lives in Liberia, but that authorities have been monitoring flights to that nation and the boy has not been on any.

When asked by e-mail Tuesday if police suspect foul play or believe that Barway may have come to harm, Revering replied only that at the news conference, "I was asked if the dad was a suspect and I stated, 'Yes.' "

Pastor Harding Smith of Spiritual Church of God in Robbinsdale, who has been involved with the investigation, was on his way to the Collins home Tuesday night.

Smith said that because the investigation is ongoing, he cannot comment on his role with the case, but that he would be "disheartened to know if any family member played a role in Barway's disappearance."

During a Monday night vigil in front of the apartment complex, Pierre Collins and Barway's stepmother, Yamah, pleaded for his safe return. "Barway has been gone for a very long time now," Pierre told a crowd of about 40 people, many from the north metro area's Liberian immigrant community. "We are begging and asking everyone to look out there."

Police had said they did not believe foul play was involved in Barway's disappearance. Eventually, however, Crystal police called on the FBI, the BCA and the Hennepin County Sheriff's Office for help.

The Crystal Police Department is offering a $1,000 reward for information regarding the disappearance.

Karen Zamora • 612-673-4647

Twitter: @KarenAnelZamora