I have downloaded some True Type Font (ttf) fonts and pasted them in the directory
/usr/share/fonts
after that I restarted LibreOffice writer but I don't find the new fonts in the font list. No better result after rebooting.
I copied the files to
usr/share/fonts/truetype
and again restarted LibreOffice writer, but still they aren't on the font list.
I've tried in another way. Opened the fonts with font viewer and click on the install but the result is the same.
Latest
I've just found that those specific fonts are installed on my system, they present on gedit's font list, but not in the LibreOffice font list. So, may be the problem is with LibreOffice.
Very surprising and irritating issue indeed.