We thought we had accounted for all the blood on the hands of the Tsarnaevs, but we were wrong. Thousands of miles from Boston, Omar Mateen shot 103 people at point-blank range, splattering their blood on the floor and the walls of Orlando’s Pulse nightclub. He killed 49 of them in the name of ISIS, inspired, he said, by the murderous Tamarian and Dzhokhar.

The Tsarnaevs horror didn’t end on that Watertown street and in a Boston courtroom. We now know that some, like Omar, see them as terrorist role models. “Blood will have blood,” Shakespeare’s Macbeth predicted. Blood spilled will lead to more blood spilled. At 2 a.m. Sunday morning, three years after the marathon bombing, Omar Mateen linked the brothers – his “homeboys,” he said – to his own hate-fueled mission.

He copied their shocking plan – twin bombs at the finish line, a tragic ending of a joyful family event. Mateen trained his bullets on the nightclub dancers at closing time – a deadly finale for a special night of revelry for Orlando’s LGBTQ community. Before the Orlando SWAT team took him down in a hail of gunfire, Mateen snuffed out the lives of two New England natives – 23-year-old Stanley Almodovar and 37-year-old Kimberly KJ Morris.

But, most importantly, he wanted to stamp out the symbols of an inclusive community which freely embraces its freedoms to do and to be. Orlando’s lesbian, gay, bisexual, transgender and queer community apparently offended him – his father recalling his anger at seeing two men kissing. Like the Tsarnaevs, Omar Mateen acted alone, drawn to the siren song of ISIS' online recruiting. FBI Director James Comey confirms Mateen was inspired, but not directed, by ISIS. Still, ISIS claimed him as a soldier, urged others to follow in his footsteps, and promised rewards tenfold for attacks against the West carried out during this holy month of Ramadan.

In this moment of sadness, some hard truths. Many of the most dangerous terrorists are homegrown – hidden in plain sight. And the fact is there is simply no absolute defense against them. No wall, no ban, no data-mining, no super-militarized police department can completely keep us safe. Our best protection – actualizing our principles: We can say out loud that we will not tolerate prejudice of any kind, we can tighten loopholes in our gun laws and have the courage to stop the sale of the kind of assault rifles carried into war by our troops. It will not be easy. Almost immediately after the Orlando tragedy, sales of assault rifles flew off the shelves.

Boston emerged strong from the marathon bombing, just as Orlando is now declaring itself unbreakable from the deadliest mass shooting in U.S. history. In the hours after the killings, locals flocked to a blood bank to give blood for the seriously injured victims. They stood in a line that stretched for miles, the scorching Florida sun no match for their determination to give back the vital life force taken by a disturbed killer. A visual affirmation that no bombs or bullets can stop the pulse of a community standing up to terror.