'Formulated a plan to kill': Husband waits for scientist wife to come into another room where he repeatedly stabs her with kitchen knife, cops say

Left: James Martin (Johnson County Jail). Right: Amber Martin (Amber Martin/Facebook).

A 47-year-old Iowa man allegedly "formulated a plan" to kill his wife and repeatedly stabbed her in their apartment, according to authorities.

James Martin stands accused of first-degree murder in the death of 41-year-old Amber Martin in Coralville, which is just outside of Iowa City. Cops responded around 6:40 a.m. Friday to an apartment in the 2800 block of Spring Rose Circle for a stabbing. When officers went inside the apartment, they found Amber Martin suffering from numerous stab wounds.

Paramedics pronounced her dead at the scene.

According to a criminal complaint obtained by Law&Crime, James Martin admitted to killing his wife.

"In the hours leading up to the defendant killing the victim, the defendant formulated a plan to kill the victim," detectives wrote. "The defendant retrieved a kitchen knife and surprised the victim as she exited another room and stabbed the victim repeatedly."

Cops took the suspect into custody after evidence was consistent with James Martin's statements and observations by a witness. Detectives did not publicly divulge a possible motive for the attack.

The victim worked as a medical laboratory scientist supervisor for the University of Iowa Health Care system.

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"My entire staff and I are shocked and horrified by Amber's death," her boss Connie Floerchinger told Muddy River News. "She was sweet, smart and had an amazing personality. She had only been with us since September but we all feel like we had known her forever! Our community and the field of clinical microbiology will not be the same without her."

Before that, both the victim and her husband reportedly worked for the Quincy Medical Group as medical researchers. Ann Ostermiller told Muddy River News she trained Amber Martin in her position.

"Amber was such a wonderful woman," she told the outlet. "She was vivacious, kind, and loved by all her coworkers. Jim was quieter and more reserved. This murder is beyond the comprehension of those that knew them when she worked at QMG. They seemed to be such a close and loving couple. I cannot imagine what transpired to change their relationship so much."

James Martin is at the Johnson County Jail on a $1 million bond.