Just as the #JeSuisCharlie hashtag was used to stand in solidarity with the magazine, #JeSuisAhmed has also become a rousing point on social media to memorialise the slain policeman.
Police officer Ahmed Merabet was lying wounded on the pavement outside the office of Charlie Hebdo when one of the masked gunmen walked over and shot him point blank before driving off.
French newspaper Le Figaro said amateur video footage showed one of the gunman asking Merabet: "Tu veux nous tuer?" ("Do you want to kill us?") to which Merabet replies: "Non, ç'est bon, chef" ("No, it’s OK mate"), before he is killed.
Mr Casters told BBC he started the hashtag because he wanted people to not forget that a French Muslim was a victim in the Paris attack.
"It is a snub to the stigmatisation of Islam and a reminder that Muslims in France are not all Islamist radicals," Casters told the BBC in an email.
The hashtag since has been used over 40,000 times.
The policeman's death also drew the attention of UN secretary-general Ban Ki-moon, who told reporters: " All of us were deeply moved by the many images from yesterday’s despicable attack in Paris. Perhaps none was as horrifying as that of a French policeman ruthlessly executed on a sidewalk."
Others have joined the conversation with #VoyageAvecMoi ("Ride with me") pledging to stand with their Muslim friends against Islamophobia.
This was inspired by #illridewithyou which trended on Twitter following Sydney's Martin Place siege in December.