A body found in the Mississippi River over the weekend has been identified as that of a 10-year-old Minnesota boy who has been missing for nearly a month, and police said Sunday that the boy's father is a "primary suspect" as the case becomes a homicide investigation.

Authorities said the body of Barway Collins was found Saturday, about 10 feet from the river's edge in Brooklyn Center. Crystal, Minnesota, Police Chief Stephanie Revering said authorities have electronic evidence that shows the boy's father, Pierre Collins, was in that area at the time the boy disappeared. She did not elaborate on the nature of that evidence.

"This location is consistent with our knowledge of Pierre Collins' activities on March 18 and he remains a primary suspect," Revering said Sunday.

The Hennepin County Medical Examiner said the cause and manner of Barway's death are still being investigated. Revering added that the case is being investigated as a homicide based on the autopsy and information from the medical examiner. She did not elaborate.

Pierre Collins has not been arrested or charged. Revering said authorities have his passport to ensure he stays in the country, and police were stationed at his apartment complex for his own protection.

Pierre Collins has said he is innocent. A phone message left at the home on Sunday was not immediately returned to The Associated Press.

In a March 25 interview with the Star Tribune, Pierre Collins said he was not home when his son disappeared and he was upset to be considered a suspect.

"I've been working with the police just to bring my son home," he told the newspaper. "I will do whatever they want just so Barway can come home. I have nothing to do with Barway's missing."

His wife and Barway's stepmother, Yamah Collins, also said she and her husband didn't know who took the boy, and they pleaded for his safe return.

The family told the Star Tribune that Barway emigrated from his home country of Liberia to stay with his father in 2011. The father said he wanted "to make him better" and for Barway to eventually go to college. Barway's mother lives in Liberia.

Barway was last seen after school on March 18. Video surveillance from his apartment complex shows he was about to go inside, but then turned around as if he was called over to the parking lot by someone he knew, and he walked away, police said last month.

Video from a school van shows that right before he was dropped off, he had said that he saw his dad and a man who he referred to as his "uncle" nearby.

Revering said earlier in the investigation that a lie detector test showed Pierre Collins was being untruthful with authorities.

Barway Collins was a fourth-grader at Evergreen Park World Cultures Community School. Volunteers have helped search for him in recent weeks. His body was found Saturday by searchers from a Boy Scout troop, who then notified authorities.