Update: Lord Gøn replied to Cientific124. Mahomet III. is indeed Mehmed III.
"Good day to you,
thank you for the information. I have vague memories that at some point I have researched a case where some king, or nobleman has killed a lot of his relatives after he assumed power, but it turned out that he did so over an extended period of time. However, as kinslaying was not uncommon among the nobility, especially in Muslim countries, I can't say, if it was this case, or something unrelated.
Now, said Mahomet III. indeed is Mehmed III., the son of Murad III., who strangled his five younger brothers, according to Wikipedia. About Mehmed it is said in various sources that he killed his 18, or 19 brothers, as well as his sisters and his father's pregnant concubines, though the murders apparently weren't carried out by himself, but by his subordinates."
Book mentioning the familicide 1 Book mentioning the familicide 2