Prince Harry first confirmed his relationship with the American actress, who is mixed race, in November 2016 by issuing a strongly-worded statement about media harassment and racism against her on social media.
Police would not say who the envelope was addressed to but said tests showed the substance to be non-suspicious.
"Prince Harry is anxious about Ms Markle's safety and is deeply disappointed that he has not been able to protect her", Knauf said then.
More Israelis believe police than Netanyahu, polls show
During his tenure as prime minister, some 15 investigations have been opened against Netanyahu to "topple me from power", he said. When Netanyahu first made his move to take over the Likud party 25 years ago, the party establishment largely dismissed him.
Why is Albertsons Purchasing Rite Aid?
The new company will operate approximately 4,900 locations, 4,350 pharmacies, and 320 clinics across 38 states and Washington D.C. And, with retail stocks in general being hammered by the disruption of online shopping, it is a buyers' market.
Freezing rain causes slick road conditions
This is bringing a return to winter conditions, with freezing rain likely holding off for several more hours. Tuesday: Rain showers likely possibly mixing with freezing rain after noon, then gradually ending.
South Africa parliament to elect Ramaphosa as president
Low growth rates and dwindling investor confidence were compounded by two credit agencies downgrading the economy to junk status. The South African currency, the rand, reaching its strongest levels in three years - at 11.6570 rand for $1 in early trading.
Jessie Diggins bringing home cross-country skiing gold
She is also one of the first women to compete in five Olympics, along with Kelly Clark, who is also in Pyeongchang. The Americans held the fastest time in the semifinals, allowing them to start on the front row for the finale.
Winter storm warning in effect for the North Fork
Sunday will see a bounce back to warmer temperatures with a high of 57 under partly cloudy skies forecast across the region. As that front drives in a brisk northwest wind (gusting over 25 mph), colder air will begin flowing into the Garden State.