A member of MS-13 nicknamed 'Animal' who earned full membership into the ultra-violent gang by killing a 15-year-old boy has been sentenced to 40 years in prison.

Federal prosecutors in Massachusetts announced that 23-year-old Joel Martinez, a native of El Salvador who lived in Boston, learned his fate on Tuesday.

Martinez will be subject to deportation after serving out his sentence in federal prison, followed by two years of probation.

He pleaded guilty in December 2017 to a racketeering conspiracy, which included the September 20, 2015, slaying of 15-year-old Irvin Javier de Paz Castro on Trenton Street in East Boston.

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Headed for the cage: MS-13 gang member Joel 'Animal' Martinez, 23 (left), was sentenced on Tuesday to 40 years in prison in the 2015 stabbing death of 15-year-old Irvin Javier de Paz Castro (right)

A screenshot from CCTV footage shows Martinez armed with a knife on the day he stabbed Castro three times in Boston as part of his initiation into the violent gang

Prosecutors say Martinez acknowledged being associated with MS-13 and bragged about the stabbing in a secretly recorded conversation, saying: 'He stared at me and he asked me if I was going to, if I was going to stab him. I told him, "Yes, the Mara rules you."'

'Mara' is shorthand for Mara Salvatrucha, which is the full name of the ruthless gang.

After Martinez knifed Castro three times, killing him, he was 'jumped in' and made a 'homeboy,' or full member of MS-13’s Eastside Loco Salvatrucha clique during an initiation ceremony that was secretly recorded by undercover agents.

When a prospective member is 'jumped in,' members of the MS-13 clique beat the new member with their hands and feet while one of the leaders of the clique counts aloud slowly to thirteen.

Martinez's defense lawyer argued for a more lenient sentence, saying that his client was forced to join MS-13 in order to protect his family members from possible retribution.

Martinez was arrested as part of Operation 'Mean Streets' targeting MS-13's netwrok

Donald Trump has made the fight against the largely Hispanic MS-13 gang one of the centerpieces of his domestic policy.

Last week, Trump stirred up controversy when he called MS-13 gang members who illegally cross the border into the US 'violent animals'.

The comment uttered during a White House roundtable discussion on immigration was initially taken out of context, leading congressional Democrats to believe that the president was referring to all immigrants.

White House Press Secretary Sarah Huckabee Sanders later stated the president was 'very clearly referring' to members MS-13 and accused 'the media and liberals' of defending the violent gang.

Trump tweeted on Friday that those media reports got it wrong intentionally.

'Fake News Media had me calling Immigrants, or Illegal Immigrants, "Animals." Wrong! They were begrudgingly forced to withdraw their stories,' the president wrote.

Thie White House's website returns a single result to people searching for the word 'animals,' and it's this statement about MS-13

'I referred to MS 13 Gang Members as "Animals," a big difference – and so true. Fake News got it purposely wrong, as usual!'

On Monday, the Trump administration doubled down on the president's previous remarks by publishing a primer titled 'What you need to know about the violent animals of MS-13,' both on its website and via an email blast to reporters.

'The violent animals of MS-13 have committed heinous, violent attacks in communities across America,' it reads, describing the Mara Savatrutcha narcotics street gang that has roots in El Salvador.

'Too many innocent Americans have fallen victim to the unthinkable violence of MS-13’s animals.'