Marine's Wife Miscarried Just Months Before She Went Missing, Friend Says

— -- The wife of a Marine who vanished nearly one month ago had suffered a miscarriage a few months before her disappearance, a close friend said. She was pregnant again at the time she was reported missing, according to police.

Police said Erin Corwin was last seen on June 28 before telling her husband she was going on a hike in Joshua Tree National Park. She did not return home that evening and her husband, Jonathan, called police the next day.

Authorities are investigating the possibility that Corwin was having an affair with her married neighbor and was pregnant with his child, according to a police search warrant.

Missing Marine Wife May Have Been Having Affair With Neighbor

Search Intensifies for Marine's Missing Pregnant Wife

The San Bernardino County Sheriff's Office is continuing its investigation, but conversations with a longtime friend of Erin's and a ranch owner that she spent time with in recent months provides a look into her day-to-day life.

Erin, who turned 20 last week while she was still missing, loved riding horses both in California, where she and her husband moved to last year and in her home state of Tennessee.

"She loved her horses and loved her family," her longtime friend Brooke Phillips told ABC News.

Phillips said that she has known Corwin for about eight years and they rode together at East TN Riding Club in Oak Ridge, Tennessee.

"She just always was laughing and having fun and trying to cheer people up," Phillips said.

The pair kept in touch when Corwin and her husband moved to Twentynine Palms, a military base in California's Yucca Valley.

In January, Corwin announced on Facebook that she was pregnant, tagging her husband and accepting friends' congratulations in the comments. Her sister confirmed to ABC News that it was the couple's first child.

Phillips said that she spoke to Corwin about the subsequent miscarriage, though she was not exactly sure when Corwin found out.

"She was really sad about it. She wanted kids. She loves kids and she thought she was really positive about it, like 'Sure, the time will come when I have kids,'" Phillips said.

According to police, that time came soon. The San Bernardino County Sheriff's Department confirmed in news release on Tuesday that she was pregnant when she disappeared.

A search warrant released by the office earlier in the investigation details how they came to suspect that the father of her unborn child may be her neighbor, another Marine named Christopher Lee.

The lengthy probable cause statement was initially released by the sheriff's office but they are now refusing to comment on the findings they included in the report.

The probable cause statement, which was filed in conjunction with a search warrant for a U-Haul truck that was being used by Lee and his wife during the investigation, details how police spoke to a good friend of Corwin's who said that Corwin was having an affair with Lee, and that Corwin "may be pregnant with Lee's child." Lee, who is now a reservist in the Marines, could not be immediately reached for comment by ABC News.

"Erin told [her friend] that Lee was worried if his wife discovered Erin was pregnant, Lee's wife would divorce him and keep him from his child," the probable cause statement reads.

Corwin's sister told ABC News that she had not spoken to her about this second pregnancy before her disappearance.

According to the probable cause statement, a different friend of Corwin's said that Corwin had told her that Lee had planned a "special day together" as a "celebration for Erin's pregnancy" that included a hunting trip.

Investigators went on to say in the official report: "It is highly likely Erin could have been harmed by an unknown firearm."

That same report says that Lee initially told investigators he knew Corwin only as an acquaintance, but later said that they "had previously kissed each other but never had sexual intercourse."

The police lay out a timeline where Corwin had told her husband that she was going to be at Joshua Tree National Park, 10 miles away from their home, for the same amount of time that Lee was scheduled to be hunting in the same park, but he told investigators that he did not see Corwin on the day she disappeared, June 28.

Her car was found abandoned a few minutes' drive from Twentynine Palms, the neighborhood where both Lee and Corwin live, and police said that they saw a single set of footprints going from her abandoned vehicle to a set of tire marks that were consistent with the tires of Lee's Jeep Cherokee.

Police do not have any official suspects or persons of interest in the case. Lee was arrested during the investigation because police discovered that he owned a potato launcher, which is classified as an illegal destructive device, and he is out on bond for that charge.

"Although suspicious circumstances have existed from the inception of this investigation there is still not enough evidence to rule out that Erin Corwin could be voluntarily missing," the San Bernardino County Sheriff's Department said in its Tuesday statement.

One person who said she knows both Corwin and Lee is Isabella Megli, the owner of White Rock Horse Rescue Ranch, a horse farm. Corwin had adopted a horse, Cassie, from the ranch shortly after she and her husband moved to California.

"She came here to find a horse, to volunteer and to enjoy herself with horse riding," Megli told ABC News. "It offered her someplace to go, peace of mind."

The horse that Corwin adopted had been abandoned and Megli said that it was "skin and bones" until Corwin took care of her and helped her gain over 300 pounds.

"In June, she came and said the Twentynine Palms Marine Corps Base would not approve Cassie coming to the base," Megli said.

Megli said that she was not aware of Corwin and Lee's alleged affair until the investigation began into Corwin's disappearance.

"Chris is wonderful. He was very good to me and he did a lot of nice things for the ranch. He would fix fences, he would drive, he would take manure, he would pet the horses. He was incredible with the horses," Megli said.

According to the probable cause statement, police interviewed Megli and she told them that Lee's wife, Nicole, had berated him in front of her at some point after Corwin disappeared, saying that he wasn't "able to keep his lies straight when he was interviewed by detectives."

"Nicole told Isabella that without a body the detectives did not have a case against them and the detectives would never find the body," the probable cause statement said.

The case is ongoing and remains a missing persons investigation.

"We are looking for a crime scene," Sheriff Department’s Specialized Investigation Division Capt. Leland Boldt said in the Tuesday statement.