Howell, a drifter, is believed to be the most prolific killer in Connecticut history and pleaded guilty on Sept. 8 to murdering six people in 2003
Serial Slayings
Credit: New Britain Police Department/AP

The Connecticut serial killer who drove a “murder mobile” and buried his victims in what he called “his garden” was sentenced on Friday to life in prison for his crimes, PEOPLE confirms.

New Britain, Connecticut, Superior Court Judge Joan K. Alexander handed down the six life terms — or 360 years in prison — for William Devin Howell, a court clerk tells PEOPLE.

Howell, a drifter who is believed to be the most prolific killer in Connecticut history, pleaded guilty in September to murdering six people in 2003, the Associated Press reports.

His victims, whom he killed over a six-month period, were identified as Melanie Ruth Camilini, Diane Cusack, Marilyn Mendez Gonzalez, Joyvaline Martinez, Mary Jane Menard, Danny Lee Whistnant.

At the time of his arrest, Howell was already serving a 15-year prison sentence for manslaughter in the death of a seventh victim, Nilsa Arizmendi, who disappeared in July 2003 from a grocery store parking lot in Wethersfield, Connecticut, the Hartford Courant reports.

Arizmendi’s remains were among those recovered at the burial site behind a strip mall that Howell referred to as “his garden,” according to the newspaper.

In court on Friday, the victims’ families reportedly recounted the pain they have endured since the murders.

Calling Howell an “animal,” Tiffany Menard, daughter of victim Mary Jane Menard, said she tried to kill herself twice from the time her mother went missing to when her remains were found.

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“He stripped away the youth from us and made me and my brother orphans,” she said. “I would see my mom on the streets thousands of times only to realize every time that it wasn’t her.”

Speaking about brother Danny Lee Whistnant, April Rich said to Howell, “You may be able to protect yourself physically in prison, but there is no weapon that will protect you from your own thoughts.”

Howell struck a remorseful tone in his own court statements, saying during his sentencing that he faces “a slow painful death in prison” because of his diabetes, according to the Courant.

“I hope that provides some comfort to each of the families,” he said.

He pleaded guilty to the six murders “to spare the victims’ families further emotional pain through a lengthy and drawn-out trial that would have taken several weeks, if not months,” his lawyers reportedly said.

Howell, who is from Hampton, Virginia, was arrested in September 2015 and charged with murdering five women and one man after police discovered their remains, according to a criminal complaint obtained by the Courant.

The complaint stated that he dumped each body in a separate plot in a wooded area behind the strip mall that he referred to as “his garden.”

According to authorities, Howell called the van he drove the “murder mobile” and later told a fellow inmate that there was a “monster inside him,” the Courant reports, citing the complaint.

Howell mutilated some of his victims and strangled others, according to authorities. They said he sexually assaulted three of the women and he bashed another woman’s face with a hammer and buried a portion of her jaw in Virginia.

If he hadn’t been caught, his arrest warrant stated, he planned to go “cross-country and kill others.”

Attempts to reach the district attorney and Howell’s lawyers on Friday were not immediately successful.