A Will County judge will decide May 5 on whether a Plainfield Township man is guilty of the 2018 first-degree murder of his girlfriend, whom prosecutors said was brutally beaten to death in Romeoville.

Prosecutors have asked Judge Vincent Cornelius to not only find George Hooper, 42, guilty of killing his girlfriend, Jennifer Underhill, 42, of Rochelle, but also find her murder was committed with “exceptionally brutal or heinous behavior indicative of wanton cruelty.”

If Cornelius makes the latter finding, it could lead to a natural life sentence in prison.

Assistant State’s Attorney Jacob Kreutzer detailed on Thursday why Hooper is guilty of first-degree murder, rather than the defense proposal of involuntary manslaughter or second-degree murder.

Kreutzer said Hooper killed Underhill because of his brewing rage and resentment toward her and not because of “sudden and intense passion,” one of the criteria required for a second-degree murder finding.

Kreutzer said Hooper spent a “vast” amount of time searching for Underhill, and he had a “thought-out” plan to inflict pain by attacking her repeatedly. He said during the attack, Hooper ripped off Underhill’s shirt and used it to tie her ankles.

“These were the actions of a cold-blooded killer,” Kreutzer said.

Kreutzer said Hooper had already suspected Underhill was cheating on him with his brother, Geremy Hooper, 40, of Villa Park, before the events leading to her death on July 23, 2018.

Hooper and his brother’s girlfriend, Amanda Weck, 41, of Villa Park, who also suspected the affair, went searching for Underhill and found her with Geremy Hooper inside of the latter’s semitrailer near a Romeoville warehouse, according to prosecutors.

Geremy Hooper testified to remembering having sex with Underhill inside the semitrailer.

Kreutzer said when George Hooper arrived, he took the license plates off of Underhill’s vehicle, which was also at the location, and put them in his vehicle. Kreutzer argued he did this to make it harder for anyone to find Underhill.

Geremy Hooper told police in 2018 that his brother smashed the window to the semitrailer and pulled a gun on him. He said he fled the scene following a confrontation with George Hooper.

Kreutzer said George Hooper ignored Weck’s pleas to leave the area, and eventually she left. When Geremy Hooper returned to the scene, George Hooper threatened to shoot him, and he left again, he said.

Kreutzer argued that George Hooper ignored Weck and menaced his brother so no one could witness him killing Underhill.

In George Hooper’s 2018 police interview, he admitted to punching Underhill more than once and demonstrated to detectives how he struck her jaw, Kreutzer said.

Kreutzer said when police found Underhill’s body, she was found in a tall brush area with her ankles tied with her shirt. That also showed Hooper was trying to conceal her death, he said.

A forensic pathologist testified that Underhill’s jaw and ribs were broken, and she had multiple traumatic injuries from her head down to her feet.

Kreutzer said the patterned bruising on Underhill’s body also indicated Hooper stomped on her.

At some point after Underhill’s death, George Hooper returned home and changed his clothes, but he never called 911, Kreutzer said. Later, at the insistence of his family, George Hooper “fled the jurisdiction” to southern Illinois, where he was apprehended, he said.

George Hooper’s attorney, Chuck Bretz, said prosecutors were taking “illogical” and “unfounded” positions and “overreaching” with the facts. He rejected prosecutors’ arguments that his client was plotting to kill Underhill.

“He was trying to find out what the heck was going on,” Bretz said.

Bretz said George Hooper was acting under “sudden and intense passion” and he was provoked after finding Underhill was having sex with his brother, and that “heightened” the impact of the emotional betrayal he felt.

“This was a spontaneous, explosive reaction to this discovery,” Bretz said.

Bretz said George Hooper was cooperative and forthcoming with police in his interviews, and he did not realize until those interviews that Underhill had died. He said his client “expressed genuine remorse.”

He said what happened was an “uncontrolled outburst” and George Hooper did not intend to kill her.

On Friday, Assistant State’s Attorney Nick Plattos said in rebuttal arguments that the facts of the case do not fit either involuntary manslaughter or second-degree murder. He said this is because the case involves a “multitude of intentional acts” that led to Underhill’s death.

Plattos said Bretz was trying to compare this case to other cases that involved death from a single punch.

“Your honor, this is a systematic beating case,” Plattos said.