BOSTON — It was an appalling crime with gut-wrenching details: An 83-year-old woman with Alzheimer’s was raped, then died three weeks later of complications she developed while hospitalized for injuries she received in the attack.

Prosecutors seemed to have an ironclad case against Robert Wade, who worked on the 500-acre pig farm in Lakeville owned by the woman and her son.

The son testified that he came home Oct. 24, 1993, and found his mother and Wade, both naked, with his mother sprawled on Wade’s bed inside his shack on the farm.

Wade was convicted of aggravated rape and felony murder and sentenced to life in prison.

But two decades later, Wade argues that he is entitled to DNA testing he claims would support his innocence. His case is the first to test the parameters of a 2012 state law that provides a mechanism for defendants to seek DNA testing after they are convicted.

The state Supreme Judicial Court will hear arguments in Wade’s appeal and a companion case Monday.

A Superior Court judge rejected Wade’s request for DNA testing on biological evidence found at the crime scene.

Prosecutors in the office of Plymouth County District Attorney Tim Cruz argue that Wade Is not entitled to DNA testing now because his trial attorney made a strategic decision not to seek testing when faced with the testimony of the victim’s son and other evidence.

“DNA evidence cannot negate the fact that the defendant was caught standing naked next to the naked and injured 83-year-old victim in the defendant’s bed in the bedroom of the defendant’s handyman shack, nor the victim’s identification of him as the perpetrator,” Assistant District Attorney Mary Lee argues in court documents.

The jury at Wade’s trial heard testimony from a state expert about serological testing that showed Wade could not be excluded as a possible contributor to semen on a swab from the victim’s body and her clothing. The serologist also acknowledged that the testing indicated the presence of blood or semen from a third person on the woman’s pants.

Wade’s lawyer, Janet Pumphrey, said that alone should entitle Wade to DNA testing.

“One has to wonder why the Commonwealth is so afraid to give Robert Wade access to evidence that every other accused or convicted person in the state has access to,” Pumphrey said.

The victim’s son testified that when he found his mother naked and sprawled on Wade’s bed, Wade said, “She came to me.”

During the trial, Wade’s lawyer said the sex was consensual, arguing that the victim was “hypersexual” because of Alzheimer’s disease.

But Wade’s lawyer argues that his trial lawyer doomed Wade with that defense because Alzheimer’s patients cannot consent to sex because of their impaired mental capability. Pumphrey said Wade has “borderline mental retardation,” which explains why he allowed his lawyer to argue a consensual sex defense even though he repeatedly said he didn’t have intercourse with the victim.

Wade also claimed that he would not have been able to have sex the day the woman was attacked because he had consumed a 12-pack of beer, a 6-pack of beer and three bottles of wine.

Although DNA testing was available at the time of Wade’s 1997 trial, it was still new and neither Wade’s lawyer nor prosecutors sought it, Pumphrey said.

Prosecutors argue that Wade has to show that his lawyer’s decision not to seek DNA testing was “manifestly unreasonable.”

But Lee said the Legislature, in passing the DNA law, did not say that every defendant who claims innocence is entitled to testing after they are convicted.

“The Legislature has set the bar low enough that truly innocent defendants should be able (to) obtain appropriate post-conviction forensic testing,” Lee said.

Wade, along with two others, had been charged earlier in the 1986 killing of a disabled man, but he was acquitted after a judge ruled his confession was inadmissible because he was drunk when police read him his rights.