A South Carolina man accused of killing his five children will use an insanity defense in his upcoming death penalty trial, his lawyers say.

News outlets report that attorneys for Timothy Ray Jones Jr., 36, have notified prosecutors of their intent for his trial, which is set to begin October 15 in Lexington County.

His attorneys have long suggested that Jones suffered from mental problems. The children's mother said he had been smoking synthetic marijuana and that she repeatedly tried to warn social workers that he posed a danger to them before they were killed.

Authorities said the father killed his children at his Lexington home in August 2014, after picking them up from school and day care. At the time, their mother, Amber Jones, was living apart from him due to marital problems. Six days later, she reported them missing and authorities began a search.

Police found Jones in Mississippi, where he was stopped for driving under the influence. In his vehicle, officers found a "large amount of blood and handwritten notes with directions" on how to kill and mutilate bodies. Authorities determined that he had been driving around the Southeast for nine days with their bodies in plastic garbage bags.

Jones later led police to a hillside in a rural area near Camden, Alabama, where he left their remains.

Court records show four of the children - Merah, 8; Elias, 7; Gabriel, 2; and Elaine, 1 - were strangled. Nahtahn, 6, was beaten to death. Jones told investigators he thought his children planned to kill him and then "chop him up and feed him to the dogs."

Amber Jones is suing the state Department of Social Services, alleging the state agency failed to safeguard her children despite repeated reports that Jones posed a danger to them. She also has filed a second lawsuit seeking damages from Lexington County retailers, alleging they sold him the synthetic marijuana product that he was under the influence of when he killed the children.