Political Wire, where I found the story this morning, has modified it slightly, saying that “An earlier version of this post linked to a source that may not be credible, although the reporting is similar.” That is the version I had used to build this story. Political Wire now cites The Week:
Before she became a senator and a top contender for former Vice President Joe Biden's vice presidential spot, Klobuchar spent eight years as the Hennepin County attorney, in charge of prosecution for Minneapolis. And while in that position, Klobuchar declined to prosecute multiple police officers cited for excessive force, and did not prosecute the officer who kneeled on Floyd's neck as he protested, The Guardian reports.
The story also makes a point mentioned in the comments:
Klobuchar did not prosecute Chauvin and other officers involved in the first death, which occurred in October 2006 while she was running for Senate. The case was under investigation when Klobuchar took office in the Senate in January 2007, and later went to a grand jury, which declined to charge the officers.
Klobuchar could have brought charges without going to the grand jury, but didn’t. From today's Star-Tribune: