The sis­ter of ac­cused double mur­der­er Lois Riess ran over her 37-year-old son pur­pose­ly with a full-size SUV in the fam­i­ly’s drive­way and in­flict­ed se­ri­ous in­ju­ries, auth­ori­ties said Tues­day.

Cynthia Grund, 58, was ar­rest­ed late Mon­day af­ter­noon at the scene in Sa­lem Township and re­mains jailed a­head of a court ap­pear­ance Wednes­day on sus­pi­cion of se­cond-de­gree as­sault and reck­less driv­ing, the Olm­sted County Sher­iff’s Office said.

The son suf­fered “sig­nifi­cant pel­vic in­ju­ries” and under­went sur­ger­y in a Roch­es­ter hos­pi­tal, said Sher­iff’s Capt. Scott Behrns. A hos­pi­tal spokes­wom­an said Ja­son Finstad was in fair con­di­tion Tues­day af­ter­noon.

Depu­ties were called to the home in the 3500 block of SW. County Road 150, a­bout 10 miles south­west of Roch­es­ter, and lo­cat­ed the son af­ter he had been run over, Behrns said.

“The vic­tim has a se­vere al­co­hol ad­dic­tion, and he was no long­er want­ed in Grund’s res­i­dence,” the cap­tain said.

Finstad was ex­treme­ly drunk while walk­ing down the drive­way, and he re­fused his moth­er’s of­fer of a ride to a friend’s house.

At one point, he said to her, “ ‘Why don’t you just run me over,’ ” Behrns said.

The son lay down in the drive­way, and Grund backed the ve­hi­cle up and in­ten­tion­al­ly ran over him, the cap­tain said.

Grund ad­mit­ted to what she did, and Behrns par­a­phrased her as say­ing, “ ‘He didn’t be­lieve I would. He has been drink­ing all day. We gave him a chance.’ ”

Riess, 57, was the sub­ject of a na­tion­al search af­ter her hus­band was found dead in their Bloom­ing Prairie home and a woman was found fa­tal­ly shot in a Fort My­ers, Fla., con­do.

She is be­ing held in the Lee County, Fla., jail and has been charged with first-de­gree mur­der in con­nec­tion with the death of Pam­e­la Hutch­in­son. Riess is ac­cused of fa­tal­ly shoot­ing Hutch­in­son, 59, be­cause she had a sim­i­lar ap­pear­ance to Riess, ac­cord­ing to charges.

Riess, whose pen­chant for gam­bling earned her the nick­name “Los­ing Streak Lois,” was on the run for 10 days un­til fed­er­al auth­ori­ties act­ing on a tip ar­rest­ed her at a res­tau­rant on South Pa­dre Island, Texas.

While elud­ing auth­ori­ties, Riess al­leg­ed­ly used Hutch­in­son’s cred­it card to pay for a ho­tel room and ord­er room serv­ice, and she with­drew $5,000 from Hutch­in­son’s bank ac­count. She also stopped at a ca­si­no in Lou­i­si­an­a, ac­cord­ing to charges.