Missing Texas sisters believed to be in Colorado with man who's person of interest in their mother's death

— -- Two young sisters who have been missing from their Texas home for days are believed to be in Colorado, potentially with a man who is considered a person of interest in their mother's death, police said.

Luluvioletta Bandera-Magret, 7, and Lilianais Griffith, 14, were last seen Saturday in Round Rock, about 20 miles north of Austin, where they both live, according to the National Center of Missing and Exploited Children. An Amber Alert was issued for them.

On New Year's Eve, police responded to a welfare check at a home, where they found the girls' mother, Tonya Bates, dead, according to ABC affiliate KVUE in Austin.

Round Rock police said today that the missing girls may be with Terry Allen Miles, 44, who police said is a person of interest in Bates' death. Miles was Bates' roommate, police said, according to KVUE.

The search for Bates and the missing children is focused on the Colorado-New Mexico border as of Dec. 30, police said. They added that have obtained surveillance video of Miles at a business in Trinidad, Colorado, on Dec. 30. The children were not seen with him in the video, according to police.

"Terry Miles, with those two girls, is a concern," Round Rock Police Chief Allen Banks said today. "The biggest part is we want to have those girls brought home.”

Police said they have received tips as recently as today about possible sightings of Miles and the children.

"The tips have included sightings of the girls," Banks said, according to KVUE. "We have received tips that people have seen the suspect, Terry Allen, and the two girls."

"We have officers working 24 hours on this case," Banks said, according to KVUE. "We all want to get 7-year-old Lulu and 14-year-old Lily home."