The search for a missing pregnant woman entered its fourth day on Monday.
Deputies said 26-year-old Melissa Sowders was last seen Thursday morning at the McDonald's on FM 1960 near Interstate 45.
The Harris County Sheriff's Office said Sowders' car was found Friday night in a parking lot near I-45 and Richie Road. Equusearch joined deputies in the search for her over the weekend.
Crews searching for Sowders Monday morning said they spotted something in the water where they had been searching. It's unclear what the sonar picked up, but a dive team will now enter the water.
Volunteers also spend Saturday and Sunday searching for Sowders.
"We have to start looking in areas where, if something happened, she might be hidden in, so we are looking in areas such as woods, streams, fields," said Frank Black, Texas Equusearch's lead search coordinator.
Volunteers are searching on foot, ATV's and even in boats, in hopes they will find the pregnant mother of four.
"You look for clothing, you look for indentations that might look like a grave, anything out of the ordinary, if you see car tracks going into a place that usually doesnt have some, you follow that," said volunteer Jane Tipps.
Homicide investigators said Sowder's cell phone has been inactive. On Saturday, her car was found just a couple of miles away from where she was last seen.
"We will continue on until we find her, or there is no other logical place for us to look," said Black.
Sowders' family said she went to the fast food restaurant to meet her estranged husband, possibly to discuss their four children. But when Sowders didn't come home to her current boyfriend or answer her phone, officers started searching for her, and said they believe Sowders was the victim of foul play.
"I want the family to keep up their hopes. We never want to give up hope until we know something for sure," said Black.
Volunteers from Texas Equusearch ended their search about 4 p.m. Monday. Over the weekend, they spotted something on a sonar image that made them want to thoroughly search this area.
Texas Equusearch founder Tim Miller said, "We got to keep looking. I don't know that we're going to be looking anywhere else right now until we truly eliminate what we're looking at here."
Relatives stopped by the creek off of I-45 near 1960 where searchers looked for any sign of Sowders. Her cousin believed the search centered here because this is near where her ex-husband lives and fishes.
"It's been too long. It's been too long. The reality is she's not going to come back alive," said Michelle Bierman, cousin. She told Local 2, "Everything is within walking distance of where he was. We fell like maybe he's just run the 18-month-old and said if you want to see the kids, then you have to come with me and we figure that's how he got into her car because she would not meet him at the house. It was only in public for her safety."
No one answered the door at the apartment of Sowders' ex-husband, Matthew Sowders.
The Harris County Sheriff's Office is not releasing details of their investigation.
Equu Search volunteers say they will search again Tuesday.
Miller said, "This is going to be a recovery. This isn't going to be a rescue. It's...I think all indications are that unfortunately something has happened to her and I'm sticking my neck out on the line and I'm not saying IF she's found. I'm saying when she's found. And I'm very, very optimistic that we're going to get her found."
Anyone with information on her whereabouts is asked to call Crime Stoppers at 713-222-TIPS.