Two days later, members of the TBI extradited Winkler to Tennessee, where she is now being held in McNairy County Jail. Their children were handed over to their paternal grandparents.
According to Johnson and other reports, Winkler did not give a motive as to why she shot her husband, sparking rampant speculation in the town and the media.
"Our concern at this point is why the crime took place," Selmer police investigator Roger Rickman told the AP. "There have been no specific accusations made by Mrs. Winkler."
Members of Winkler's defense team, led by Steven Farese, are staying mum about their client's motive, and TBI officials are not releasing any information. Farese has been contacted several times by ABC News but has not returned calls.
ABC News has reported that TBI agent John Mehr has said that a motive is known, yet won't be disclosed as of now. Only one motive has been definitely ruled out by authorities -- infidelity.
"We're hoping some clarity will be provided, and some information about that will come out soon," said TBI Officer Johnson.
According to some news reports, Farese has also hinted at an insanity defense. Winkler's defense team has reportedly had her visited by a psychiatrist, and prison guards have reportedly put her on a suicide watch.
"Perhaps over time we will better understand why this has happened," Selmer church elder Robert Shackelford said to the AP.
"Be very cautious about what you say or even what you think," Shackelford said, reportedly speaking to fellow congregants.
Members of the Selmer community and of Winkler's congregation are still reeling from the ordeal, trying to find answers as to why the murder happened. Congregants tell ABC News that in this time of grief, many are holding on to what Matthew provided them with weekly -- faith.
"This is a difficult time, there are good days and bad days," said congregation member Judy Turner in an interview with ABC News last week. "You have to have faith that everything is going to be all right. The good Lord is in charge."
Tuner said that the community had grown very close to the Winkler family, and people are heartbroken by what has been the loss of an entire family.
"It's like losing one of your own. We were close with the entire family," she said.
It is still unclear whether prosecutors will ask for the death penalty. Some legal experts say they have a very strong case.
"It's not supposed to happen that you lose a case like this," Birmingham District Attorney David Barber told ABC News.
But Barber adds that "you never know what kind of defense could come up" over the course of a case. Among other possible arguments, Barber said, attorneys could put forth an insanity defense or suggestions that Winkler was a battered wife. However, TBI officials have said that there appears to be no history of spousal abuse.
Other prosecutors say it's impossible to predict if a Tennessee jury will convict Mary Winkler.
"I don't think any prosecutor who's done this for a while thinks anything's a slam-dunk," said John Sarcone, a prosecutor in Des Moines, Iowa. "But when you have a confession it sure does help."