An appeals court on Sept. 16 overturned the 2013 rape conviction of a former military training instructor at Joint Base San Antonio-Lackland, ruling there was not enough evidence to find him guilty in the first place.

The Air Force Court of Criminal Appeals upheld other, lesser charges against Staff Sgt. Eddy Soto, including that he had sex with two former trainees while married and lied about it to investigators.

But the court ruled the sentence of four years in prison, reduction to airman basic and a dishonorable discharge should be set aside. The case will be sent back to the convening authority, who may order a new sentencing hearing, according to the 10-page opinion.

Soto is one of 30 former MTIs sent to court-martial since 2012 for sexual misconduct involving recruits and former basic trainees. Many of the cases have involved illegal but consensual relationships between MTIs and their students or former students. Only one other instructor was convicted of rape.

Soto pleaded guilty in March 2013 to making a false official statement and two specifications each of violating a general regulation and adultery for having sexual relationships with two former trainees. But he denied that he raped a former recruit, saying sex with the woman was consensual.

Prosecutors said Soto sexually assaulted the woman when she flew from her home in California to San Antonio to meet him in 2011. Soto and the woman exchanged more than 4,000 text messages and 655 phone calls, according to evidence submitted at trial. But the woman testified she was not ready for sex and made that clear before she arrived and again moments before the alleged rape.

"I tried to push him," she testified, but Soto overpowered her and she gave up.

The defense noted that the woman visited him multiple times after the alleged rape and continued to have a sexual relationship with him. She also did not report the alleged assault to authorities; investigators learned of the relationship as part of a widespread probe into MTI misconduct.

An expert witness who testified on behalf of the prosecution said the woman's behavior was consistent with someone who, like the victim, had grown up in an area of the world where teachers are highly regarded and rape victims may be isolated from their families and communities.

Soto elected to have a military judge, rather than a jury, decide his fate on the rape allegation. Military judge Lt. Col. Matthew Van Dalen convicted him of the charge.

The appeals court ruled that the woman's behavior after the alleged crime — including her visits — were immaterial to the case. The prosecution, according to the opinion, failed to prove the rape allegation at trial.

"We do not discount ... [the accuser's] testimony, and we recognize she portrayed what could have been a sinister act by" Soto, the appeals court wrote. As the woman's former military training instructor, it is possible Soto "used some combination of his coercive power ... his knowledge that she was dependent on him for shelter and transportation during the visit, his body weight, and his refusal to heed" her cues that she wasn't ready.

But it was up to the prosecution to prove Soto used physical force, according to the opinion. "The Government's evidence is too thin to satisfy us beyond a reasonable doubt that ... [Soto] used force to cause the sexual conduct."

Soto remains jailed at Naval Consolidated Brig Miramar in California while the government decides whether to ask the Air Force Court of Criminal Appeals to reconsider their ruling, Air Force spokeswoman Rose Richeson said in an email.

Thirty former MTIs have been sent to court-martial in the last 2½ years. Three were accused of rape and two — including Soto — were convicted of the charge. The third was acquitted at court-martial.

Former Staff Sgt. Luis Walker was sentenced to 20 years in prison for rape and other charges involving 10 women. He died of an apparent suicide at Fort Leavenworth in Kansas earlier this month.