Three young girls missing in Michigan since their mother was found dead at their home have turned up safe, said Saginaw police.

They were with their estranged father, 35-year-old Jose Olguin, who is now in custody.

A tip led authorities in a neighboring county to a car where the girls and the father were discovered on Tuesday, according to police Lt. Tammy Luty.

"The children are all safe and well," Luty said.

Saginaw police found the body of 32-year-old Erica Olguin at her home Monday night after she failed to pick up her 11-year-old son at school.

Police issued a nationwide Amber Alert for her daughters, 3-year-old Victoria, 5-year-old Lilliana and 9-year-old Elena.

The girls' father drove them to Elkhart, Ind., on Monday to visit relatives, according to authorities. Investigators had been on the lookout for his yellow Buick Skylark with Michigan license plate number BWW 6981 and duct tape on the passenger's side mirror.

Cops said they're investigating the mother's death as a homicide.