The father and grandmother of a man who killed his five children asked a jury on Monday to spare his life for the slayings because their family has seen so much death and sadness.

Roberta Thornsberry testified that along with losing her five great-grandchildren after Timothy Jones Jr. killed them in their Lexington home in 2014, she has also had to deal with untimely deaths of other children and grandchildren.

Defense lawyer Casey Secor asked her if the jury should sentence her grandson to death for killing her five great-grandchildren.

"No, God no. I love him. Our family has been through enough. I don't think we can take any more. This has broken us so bad I think that would be the final nail in the coffin," Thornsberry said, wiping tears from her eyes.

Later Monday, Timothy Jones Sr. also urged the jury to spare his son's life, taking off his dress shirt and tie to show the jury tattoos of all five of his grandchildren's faces covering his back.

Earlier, he testified how he had torn down the pool he built in his backyard for the grandchildren to play in after defense lawyers at trial had showed a home movie of him holding the oldest two in floaties.

"I feel more responsible than anyone," Jones Sr. said of the murders of his five grandchildren at the hands of his son.

The same jury that convicted Jones Jr., 37, of five counts of murder last week is deciding his sentence. They must unanimously choose the death penalty or Jones automatically gets life in prison without parole.

Thornsberry talked about how Jones Jr. was mostly happy as a child. She identified her five great-grandchildren from a photo of all of them in the bed during a visit to her house.

Jones' lawyers are trying to get the jury to have mercy on Jones by showing how his execution would just continue the heartache his family has endured.

Prosecutor Shawn Graham reminded Thornsberry of her testimony before Jones was convicted, in which she said he was selfish because he was an only child. Then, in a soft voice, he asked her if she heard testimony from Jones' confession about how the older children begged for their lives or said they loved their dad as he strangled them.

She cried and quietly agreed.

Jones confessed he exercised 6-year-old Nahtahn until he collapsed and died, then several hours later decided to kill the other four children . Jones said he strangled 8-year-old Merah and 7-year-old Elias with his hands and used a belt to choke 2-year-old Gabriel and 1-year-old Abigail because his hands were too big.

Earlier Monday, defense lawyers called two prison guards who said Jones has been a model prisoner in his nearly five years behind bars, ignoring horrible things said by other prisoners when they discovered who he was and what he had done.

They also called psychiatrist Donna Maddox who has treated Jones and said his schizophrenia is getting worse, taking away his outward emotions and his intelligence.

When he killed his children, Jones was a computer engineer making $80,000 a year. Now he is scoring below average on a number of intelligence tests, Maddox said.

Jurors have heard nearly four weeks of heart wrenching testimony in the case, from the mother of the children breaking down in sobs that she didn't do more to help her kids to teachers who said they have nightmares and can still see the children they taught in the halls of their school.

Jones' own father testified he feared his son would break down mentally because his mother has been in a mental institution with schizophrenia for more than two decades and a court appointed psychiatrist testified Jones mental problems came from synthetic marijuana, not a disorder in his brain.

The trial is being livestreamed from the Lexington County courthouse.

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Follow Jeffrey Collins on Twitter at https://twitter.com/JSCollinsAP .