TULSA, Oklahoma - The first witness in Shaynna Sims' trial took the stand Tuesday. Sims is charged with wrongfully dissecting a woman's corpse in 2015, and the jury was seated Tuesday morning. 

Both the prosecution and defense gave their opening statements to jurors Tuesday afternoon, and both focused on "motive."

Lynch died in spring 2015 of natural causes, and prosecutors said Sims mutilated Lynch's corpse in her casket at the funeral home, cutting her face and cutting and removing Lynch's breasts and a toe.

Prosecutors claim Sims intentionally made Tabatha Lynch "look like a clown" in her casket - because Sims' husband was having an affair with Lynch.

But, the defense said Lynch's mother was unhappy with Lynch's appearance and allowed Sims to fix a few things, including her jewelry and makeup.

The defense said when Sims went to Lynch's home to get supplies, police arrested her after Lynch's children called the police.

Sims' attorney said the evidence will most likely show his client did mess up Lynch's makeup and even cut her forehead.

But he denies Sims removed Lynch's breasts and a toe.

The funeral home manager testified his staff didn't notice Lynch's body was tampered with until later in the evening after Sims visited the funeral home.     

Prosecutors said a police officer will testify a pocket knife, scissors, and a box cutter with locks of Lynch's hair on it were found with  Sims when she was arrested.