A 50-year-old man pleaded guilty Tuesday in a plan to kill his ex-partner with a ricin-filled water gun, the U.S. Attorney's Office for the Middle District of Florida said in a statement. 

According to the criminal complaint in the case, investigators were alerted to Kissimmee resident Kevin Deane Jones' plan in December, after a witness warned his alleged target in a series of text messages.

Jones allegedly told the witness, who was not named in the complaint, that he planned to manufacture ricin, an extremely toxic poison, put it into a water gun and spray his former partner in the face when she visited Florida for a family member's graduation.

He then planned to "go on vacation immediately after ... so he would have an alibi when victim died," court documents said.

On Dec. 17, Osceola County Sheriff's Office deputies interviewed the witness who "confirmed sending the text messages to victim because witness was scared for their lives," the complaint said. 

Investigators reported that Jones and the alleged victim had been in a longterm relationship, but had been separated for more than a year.

"Victim stated that Jones had become increasingly angry due to child custody issues," the complaint said.

At least one of those issues was the alleged victim's refusal to send the couple's juvenile daughter to Florida for Christmas, court documents said. 

The witness told investigators that Jones had been ordering items on Amazon.com for several months in an attempt to manufacture ricin himself.

Kevin Deane Jones, who pleaded guilty Tuesday in a plan to kill his former romantic partner with ricin sprayed from a water gun, allgedly told a witness that he planned to go on vacation after the attack so he would have an alibi with his victim died. (Photo courtesy of Osceola County Sheriff's Office)

The unnamed witness told deputies that Jones was allegedly storing the materials he used to manufacture the poison in his apartment.

According to the Centers for Disease Control and Prevention, ricin is found naturally in castor beans, which can be processed to extract the poison.

Death from ricin poisoning usually takes place 36 to 72 hours after exposure, depending on the delivery method, the CDC said on its website. 

There is no antidote for ricin poisoning.

When Jones was taken into custody by Osceola County Sheriff's deputies on Dec. 17, investigators reported finding a plastic water gun filled with an unknown liquid alongside four vials that were also filled with liquid.

The FBI later tested the liquid and confirmed the presence of ricin, the complaint said.

Jones allegedly admitted to investigators that he ordered all the supplies to make the poison and that he started making ricin "because he was angry" with his former partner.

He was initially charged with manufacturing a weapon of mass destruction. A convicted felon, Jones also faced firearms charges after deputies located numerous weapons and ammunition in a storage unit, the complaint said.

On Tuesday, he pleaded guilty to unlawful possession of ricin, a biological toxin, and possession of two firearms as a convicted felon. 

He faces a maximum of 10 years in federal prison on each count.