A glimmer of hope in the search for Kristin Westra turned to disappointment Thursday after the investigation of a possible sighting of the missing Maine elementary school teacher revealed it was not her, officials said.

The possible Thursday sighting, one of many leads, was no longer being considered, Cumberland County Sheriff’s Office Capt. Scott Stewart said.

Westra, 47, of North Yarmouth, was last seen at her home by her husband, Jay Westra, on Sunday, Cumberland County Sheriff’s Office officials said earlier this week. Jay Westra said he woke up Monday morning with his wife nowhere to be found -- even though her vehicle, cell phone and keys were still in the house, police said. Jay Westra then drove to the fire station to report her missing, according to the Portland Press Herald.

Police have said nothing to indicate foul play was involved in Westra’s disappearance. Stewart, however, said authorities were investigating every possibility.

“We wouldn’t be doing our job if we didn’t always keep that on the table,” he said.

Search dogs scouring the area behind the Westras’ home were slowed by dense brush and trees, the Portland Press Herald reported. Authorities have said no clues have turned up so far in the search around a wooded area in a 1.5-mile radius of the home.

There was no suggestion Westra got into a vehicle, and evidence indicates she was traveling on foot, Stewart said.

Jay Westra told NBC News Wednesday his wife was scheduled to have blood work done Monday and then planned to return to her workout routine – which had been disrupted by the start of the school year and renovations to the couple's home.

“She told me she felt better. We had a plan,” Westra said. “Kristin is a person who, when she has a plan, she sticks to the plan and she follows through and she does things well, every time.”

Jay said his wife was restless the morning she disappeared. He said he thought Kristin had moved downstairs to sleep to avoid waking him. But when he later awoke, she was nowhere to be found.

When asked about Kristin's state of mind, Jay said, “Kristin is a rock. She sees a problem and she’s not afraid of problems. She knows how to solve problems.”

"Kristin is a rock. She sees a problem and she’s not afraid of problems" — Jay Westra

Jay Westra said he thinks his wife may have left through the back door. He said the door was open a few inches and it has a faulty lock, which makes it hard to close.

Westra, a teacher at Chebeague Island School, is described as 5-10, 140 pounds and having brown hair and brown eyes. It wasn’t clear what she was wearing at the time of her disappearance. She has two children – a 9-year-old daughter and a 16-year-old stepson.

The Associated Press contributed to this report.