Tragic and newsworthy, as reports from social media site show — and not just for its celebrity quality.  Oscar Pistorius made headlines a few years back when the double-amputee demanded and received the permission of the International Olympic Committee to compete in track against able-bodied runners.  Police in South Africa arrested the athlete this morning after a shooting killed his girlfriend Reeva Steenkamp, who spent this week tweeting about … domestic violence awareness:

Olympic athlete Oscar Pistorius has been charged with murder in the shooting death of his girlfriend, police and the woman’s talent agent said Thursday.

Capacity Relations talent management firm said 29-year-old model Reeva Steenkamp was the victim of the shooting.

Pretoria Police spokeswoman Denise Buekes said officers received a call in the middle of the night saying there had been a shooting at the 26-year-old double-amputee runner’s home in a gated housing complex in the capital, Pretoria. A 9 mm pistol was recovered and a murder case opened against Pistorius. …

Buekes said police had been called to the home on previous occasions over “allegations of a domestic nature,” but she would not elaborate on when those incidents at Pistorius’ house occurred, or who was involved. She said there were “no signs of forced entry” at the house Thursday morning.

At first, a rumor spread that this was a Valentine’s Day surprise gone horribly wrong, but police say that theory didn’t come from them, nor does it fit the facts on the scene.

http://twitter.com/#!/MicahGrimes/status/302017845032787968

Twitchy has a couple of posts on Steenkamp’s social-media messages over the last few days:

http://twitter.com/#!/Thoryi/status/302011798045995008

This tweet from Sunday was especially tragic:

http://twitter.com/#!/reevasteenkamp/status/300503848022310912

Advertisers have already begun backing away from Pistorius, and it may not be soon enough.  Be sure to stick around to the end, though, as one CBS analyst wonders whether the gun was to blame, rather than the man allegedly holding it.  Expect to hear more of that kind of analysis as the day wears on, too.