A 64-year-old Wisconsin man maintains his innocence but admits there is enough evidence to convict him.  Based on that Alford plea, a Fond du Lac judge has given Dennis Brantner a 10-year prison sentence in a 1990 murder case.  Prosecutors say Brantner strangled 18-year-old Berit Beck while she was traveling with him from her Sturtevant home to Appleton to attend a work-related seminar.  Her van was found a few days later, but it was a month before her body turned up in a ditch near Waupun.  The charge against Brantner was reduced from intentional homicide to second-degree reckless homicide as part of a plea agreement.