Everyone thought Dorothea was a sweet old lady. Then they found 7 bodies in her backyard.

With her colourful cardigans, pearl necklaces and neat grey perm, Dorothea Puente's boarding house was in hot demand. 

She was the sweet old lady who took in society's most vulnerable - the disabled, elderly and homeless, in Sacramento, California. She put a roof over their head, food in their belly and gave them a place to call home. 

Social workers went out of their way to get their clients a spot there. But behind closed doors it was a nightmare.

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Dorothea Puente was lying about everything. Her age (she was much younger than she pretended to be), her name, her background (she had a criminal rap sheet) and motive in running the boarding house. 

She wasn't 'giving back to society,' she was stealing her tenants' social security and disability checks and murdering them - burying their bodies in her backyard.

She murdered up to nine people before finally the disappearance of one particular tenant became her undoing. 

Four husbands and an obsession with lying.

Dorothea was married by the age of 16. She had two daughters with her first husband, but the first was sent off to live with family and the second ended up in an orphanage. 

As true crime author Genie Ortiz told Mamamia's True Crime Conversations, "She was never able to bond with any of her children. She just could not handle motherhood, like she had no maternal feelings."

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With every new husband, she re-invented her identity. She pretended to be Portuguese, then Mexican, then an Egyptian-born Muslim woman of Israeli descent. 

It was her second husband who sent her off to a psychiatric hospital in 1961, where she was diagnosed with being a pathological liar with an unstable personality. 

She started committing crimes early in her life, starting with forgery and running an illegal brothel. 

While she served four months in prison for trying to buy shoes with another woman's paychecks, she wasn't really reprimanded for the brothel. 

As Ortiz explained, "she was very, very good at getting people to sympathise with her, she pretty much got off scot free".

The 'Death House landlady'.

In the early 70s, Puente bought an Old Victorian house in Sacramento that she turned into a boarding house for the vulnerable.

She created a class system within her home; those who could provide her with more money, got better living conditions. 

While in prison, one of her former tenants realised he hadn't been receiving his disability check. It was discovered that Puente had been cashing it. In fact, police found she'd forged 34 tenant's checks. 

Dorothea Puente. Image: Netflix.

She was given five years' probation and ordered to pay $4,000 in restitution. Her boarding house was no more. 

So she started up another one - illegally. She rented a home and picked up where she left off, but this time she wasn't just forging checks. 

It started with drugging and stealing from her victims. 74-year-old Malcolm Mackenzie reported sharing a drink with her at a bar, but when they went back to his house and he found himself in a state of paralysis. He watched Puente steal cash, his watch and the ring off his finger. 

Then she escalated to murder. 

In February 1988, a social worker named Judy became concerned about a client of hers called Alvaro "Bert" Montoya who had been living at Puente's boarding house. She was struggling to get in contact with him. At first, Puente told her Bert was in Mexico with her brother, then it was claimed family had come to pick him up. 

The disappearance of Bert, led to the discovery of the bodies. Image: Netflix.

The police were called, and while at the house investigating, another tenant slipped them a note. It read: "She wants me to lie to you".

They convinced Puente to let them dig in her backyard to appease the social worker, and it was there that they discovered human remains. But they were too decomposed to be Berts'. As police continued to poke around in her backyard, Puente made a run for it under the guise of going across the road for a coffee. 

Detectives found seven more bodies, including that of Bert Montoya. 

Puente was eventually tracked down at a motel in Los Angeles, and a TV crew managed to get a brief interview with her before she was put on a plane home. 

"I used to be a very good person, at one time," she told them.

Convicting a killer.

Despite the seven bodies in her backyard, and being linked to two other deaths - a lover whose body was found near a river, and a friend whose death was originally put down to suicide - Dorothea was only found guilty of three murders. 

Dorothea admitted to forging checks, but claimed her tenants died of natural causes and illness. She admitted that she buried them in her backyard because her boarding house violated her parole and she didn't want the death to raise suspicion. 

But in court it was argued that she used sleeping tablets to put her tenants to sleep, then she suffocated them and hired convicts (or convinced tenants) to dig holes in her backyard. 

The victims were both male and female and ranged in age from 51 to 78.

Dorothea Puente leant into the 'grandma' image, and it worked for many years. Image: AAP

As Ortiz explained to True Crime Conversations, "[she killed some] because she wanted to keep the ruse [that she was stealing checks] going for as long as she could, and she couldn't do that if these tenants complained to someone that she was taking their money. If they expressed they were unhappy about this, she would have them killed.

"Some she had them killed just because she found them annoying."

Eleven jurors were convinced of her guilt in the six other counts of murder she wasn't convicted for, with just one juror leaving them at a stalemate.

The jury deliberated for 24 days until the judge declared a mistrial on those counts.

She was spared the death penalty and instead was sentenced to life imprisonment without the possibility of parole.

She died aged 82 in 2011, but even in prison she was able to manipulate others.

"Other inmates saw her as this warm maternal figure. I believe some called her 'mum' and 'grandma'," Ortiz told True Crime Conversations. 

"It's like wherever she went she really wanted to create this image of herself as someone that can be admired, and this did not stop in prison...even though there was nothing monetarily to gain from it."

Feature image: AP Photo/Walt Zeboski/AAP.