Heather Smith was afraid of her husband and frightened that he would take custody of their children if she ended their relationship, a family member said Tuesday.

The relationship of Heather and Joel Smith, whose bodies were found Sunday in Saco along with those of their three children in a murder-suicide, was complex and fraught with difficulties, said Jennifer Montez, Heather Smith’s sister-in-law.

Montez said that since Heather and Joel Smith began dating, he had a tendency to control the relationship, a habit that intensified when the couple married in 2010 and had two children together. Montez, 36, of Laveen, Arizona, is married to Heather Smith’s brother and described how she and other relatives would receive panicked, late-night phone calls from her sister-in-law.

“She was afraid of him,” Montez said. “And she was afraid of losing her children. So she actually sacrificed her happiness and her life because she was not willing to be a part-time mom, she wasn’t willing to see her kids only once every three weeks.”

There were other demons that plagued the couple, factors that Montez said contributed to the family’s strife.

“I’m not going to lie, they were both alcoholics,” Montez said. “That’s where some of the money problems happened.”

Montez, in a nearly hour-long interview with the Portland Press Herald, disputed the assertion that her sister-in-law was a drug addict, and that allegations of her opioid use only emerged about two weeks before the couple’s death. For the majority of their relationship, Montez said, Heather Smith maintained the family’s only stable income while her husband sought construction work in Arizona, and later in Maine, often only securing sporadic employment.

Much of their disharmony, and Heather Smith’s fear, centered on the raising of their three children, Montez said.

Heather’s oldest son, Jason Montez, 12, was born in Arizona before Joel and Heather met; his biological father has never been in the picture. During that time, Heather lived with her mother, who cared for Jason when Heather worked.

When Heather and Joel got together, they moved into an apartment within a matter of months, according to Montez.

The Montez clan, with several branches of the family within about a 30-minute drive of one another in cities around Phoenix, stayed in close touch. Poolside barbecues and extended family meals were at least weekly occurrences. Everyone knew what was going on with everyone else.

At first, the family thought Joel was good for Heather, and that she seemed happy. The families started to get to know each other when Heather announced in 2007 that she was expecting a child with Joel. They named him Noah, who was 7 at the time of his death.

When the baby was born, the Montez family tried to welcome Joel into the fold, but he was distrustful, Montez said.

He restricted the family’s access to Noah, asserting more control than he did with Jason, who was raised with help from the extended Montez family before Joel met Heather, Montez said.

Visits with Noah were allowed only at Heather’s and Joel’s home; family members were not allowed to take him overnight, or for day trips or car rides. Heather also was noticeably absent from holiday gatherings and family parties.

“He said he was a better parent than her, even though she already had a child and he didn’t,” Montez said. “If we bought (their children) a toy and he didn’t like it, they couldn’t play with it.”

Although he was holding three jobs in the days before he used a 12-gauge shotgun to kill his wife and their children July 26, Joel struggled to maintain steady employment, and it was on Heather’s steady income that the family often scraped by, Montez said.

“Unfortunately, they continued their relationship and had another child, even though they had so much turmoil,” she said.

Montez believes the couple’s move to New England was spurred by a 2009 vacation to see Joel’s father, who lives in Maine. It was a rare getaway from parenthood, Montez said – Jason stayed with Joel’s mother.

“We were not allowed to have him,” she said.

The visit was recorded in an album of Facebook photos, in which a pregnant Heather posed for pictures in Old Orchard Beach with her husband, and at an arcade. It was fall, and the leaves were turning brilliant shades of red and orange. When they came back to Arizona, Montez said, the idea to move to Maine percolated.

“They kept talking about it, ‘We’re thinking about moving there,’ ” Montez recalled. “I said, ‘Your problems are going to follow you.’ ”

In hindsight, Montez believes the move to New England was designed to cut Heather off from the support network and familiarity of Arizona.

“He moved her to Maine to isolate her so she would feel she had no resources and would feel trapped,” Montez said. “He isolated her from all her family and all her friends.”

Once they settled in Saco, Heather found a position in a doctor’s office and Joel again sought work in construction.

Both parents were drinking heavily every night, and the stress began to affect Heather’s work performance, Montez said. Heather was getting in trouble, and managers gave her fewer hours. Then she lost the job.

When she was fired less than a year ago, Joel found positions as a handyman for the RiverView Apartments complex where they lived, at a separate apartment building, and working part time at Target.

The Montez family knew Heather and Joel were struggling. The couple asked to borrow money from family members. Heather, who was unhappy in the relationship, told Montez that she felt powerless to escape, despite repeated offers by her family to help her do just that.

Early in 2014, she told Montez about a plan to use a portion of the couple’s forthcoming tax return to take her children and get an apartment for herself.

The time came, the money arrived, but Heather’s plan never materialized.

The last time Montez heard news of her sister-in-law was July 15, when Joel called Montez’s husband to tell them that Heather was checked into a hospital because she was apparently in withdrawal from opioid use.

The family was alarmed, but Joel sounded calm, Montez said. He told them he had taken the children to his father’s house, and removed his guns from the residence. He took Heather to the hospital, and was looking for rehabilitation facilities where she could get clean.

Montez tried to help, looking up names of clinics in the area, but couldn’t get in touch with her brother-in-law.

Two weeks later, Montez learned they were all dead.