An Indiana man wanted for questioning in a double murder of his estranged wife and sister-in-law has died of an apparent suicide in Arkansas, police say.

Jonesboro Police Sgt. Cassie Brandon said Sunday that 29-year-old Darrel Jackson was found dead Friday afternoon inside a car in Jonesboro with an apparent self-inflicted gunshot wound to the head.

A police report says a Smith and Wesson 9-mm handgun was recovered at the scene.

Orphaned: Police believe Darrel Jackson, 29, killed his wife Mallory (seen together with their daughter) and her sister in a double murder-suicide Friday

Mallory Jackson (left), 27, and her sister Meredith Opel, 20 (right) were found dead from unspecified injuries in their Indianapolis home

Jackson was wanted in connection to the deaths of sisters 20-year-old Meredith Opel and 27-year-old Mallory Jackson; the latter was the suspect's estranged wife and the mother of his young child.

According to police, the women were found dead Friday with trauma to their bodies, but the causes of deaths are undetermined.

Investigators believe Jackson killed his wife and her sister at a home in Indianapolis, then drove nearly 400 miles to Jonesboro, where he had relatives.

He parked his 2011 Nissan Sentra behind his family's home, then sent his father a text message saying 'he could not take it no longer.'

At around 2.40pm local time on Friday, Jackson's father and brother emerged from the house and found Darrel dead in the front seat of his car.

Four hours later, police in Indianapolis discovered the bodies of Jackson's wife and her younger sister in a home in the 4500 block of Stone Mill Drive.

Troubled marriage: Police had recently been called to the Jacksons' home for a domestic dispute. The couple tied the knot in October 2015

Ominous: Darrel Jackson was found dead from a gunshot wound to the head behind his father's home in Jonesboro, Arkansas, shortly after sharing this photo of the house and writing that it was the place where he had 'first learned to shoot hoops'

Police would only say that the two women suffered 'apparent trauma,' reported The Indianapolis Star.

According to her obituary, Mallory Jackson worked as a licensed practical nurse for American Senior Communities at Rosewalk Village who will be ‘fondly remembered as an honest and hard-working person who was fiercely loyal to those she loved and those who loved her.’

She is survived by her and Darrel Jackson's young daughter, Camilla Rose.

Her sister Meredith was a senior at the University of Southern Indiana, where she was a Presidential Scholar majoring in sociology and political science.

‘Meredith was determined to make a difference in the world. She was a free spirit, joyful, adventurous, loyal, goal oriented, and inspiring,’ the obituary read.

Tragic loss: Mallory Jackson, a mother-of-one, worked as a licensed practical nurse (left). Her sister Meredith was a senior at the University of Southern Indiana, where she was a Presidential Scholar majoring in sociology and political science

According to his Facebook page, Darrel Jackson married Mallory Opel in October 2015, and the two welcomed their daughter in early 2016.

Police said they were familiar with the young family, having been called to their home on Stone Mill Drive recently for a domestic dispute, the details of which have not been disclosed.

Final post: Jackson, 29, lamented on Facebook before his suicide that meant 'nothing to this world'

On the day of the double murder-suicide, Jackson posted a despairing, rambling status update on his Facebook page, which opened with the words: 'Nothing to this world.'

He went on to write: 'no support, no prospects, earning a bachelor's earned me even less progress. No need for my Talents or Wisdom, Corporate America must have a predetermined vision. My only Motive was to overcome and inspire, but as slamming doors became rhythmic, my hope soon expired.

‘Before you judge me take a second to realize, all the faith you could have restored before the demise.. Look Around, There are still more living and determined individuals with nothing to lose, a progressive drive, and everything to gain. Assist when possible! Without it, They may soon become nothing to this world.’

About 20 minutes earlier, he posted a photo of his father's house in the 100 block of North Drake Street in Jonesboro, Arkansas, writing ominously in the caption: 'Where I first learned to shoot [hoops], 20 years ago!’