Edit in JSFiddle

<div id="map-div" style="width:850px;height:830px;"></div>

map = new OpenLayers.Map({
            div:"map-div",
            projection: new OpenLayers.Projection('EPSG:900913'),
            'displayProjection': new OpenLayers.Projection('EPSG:4326')
        });
        var osm = new OpenLayers.Layer.OSM();
        map.addLayer(osm);
        map.zoomToMaxExtent();
        var zoom=13;
 
        //Enter lat/long for a point in DC (taken from DC crime data)
        var longitude = -76.9319905496493;
        var latitude = 38.9096978354199;
        var centerlonlat = new OpenLayers.LonLat( longitude, latitude );
        centerlonlat=centerlonlat.transform(map.displayProjection, map.projection);
        map.setCenter(centerlonlat,zoom);        
        
        layerStyle = OpenLayers.Util.extend({},OpenLayers.Feature.Vector.style['default']);
        pointLayer = new OpenLayers.Layer.Vector("Layer Name", {style: layerStyle});
        map.addLayer(pointLayer);
        
        var crimeStyle = OpenLayers.Util.extend( {}, layerStyle);
            crimeStyle.fillColor = "blue"; //the main color of the shape
            crimeStyle.graphicName = "square"; //other good shapes are "star", "circle"
            crimeStyle.pointRadius = 25; //controls the size of the marker
            crimeStyle.strokeColor = "blue"; //the border color of the shape
            crimeStyle.strokeWidth = 3; //border width
            crimeStyle.fillOpacity = 1; //from 0 (transparent) to 1 (opaque)
            crimeStyle.graphicOpacity = 1; // from 0 (transparent) to 1 (opaque)
            crimeStyle.externalGraphic = "http://publicdatapublic.org/images/gun.png";
            
        var altcrimeStyle = OpenLayers.Util.extend( {}, crimeStyle ); //copy crimeStyle and modify
            altcrimeStyle.rotation = 0; //0 to 360 degrees... this doesn't work as well for circles
            altcrimeStyle.fillColor = "red";
            altcrimeStyle.graphicName = "square";
            altcrimeStyle.strokeColor = "red"; //the border color of the shape
            altcrimeStyle.fillOpacity = 1;
            altcrimeStyle.graphicOpacity = 1;
            altcrimeStyle.strokeWidth = 3;
            altcrimeStyle.externalGraphic = "http://publicdatapublic.org//images/crimescene.png";
 
        //create 3 points where crimes occurred
        crimePoint1 = new OpenLayers.Geometry.Point(longitude,latitude).transform(map.displayProjection, map.projection);
        crimePoint2 = new OpenLayers.Geometry.Point(-76.969508906507,38.8707434223516).transform(map.displayProjection, map.projection);
        crimePoint3 = new OpenLayers.Geometry.Point(-76.9738564118361,38.8955441398405).transform(map.displayProjection,
map.projection);
 
        //create feature variable for crimePoint1
    crimePoint1Feature = new OpenLayers.Feature.Vector( crimePoint1,null,crimeStyle );
    
    //add attributes to crimePoint1
    crimePoint1Feature.attributes = {
        name: "Theft",
        description: "Reported 1/25/2006 at 4900 block of Minnesota Avenue NE",
        wikiPage: "http://en.wikipedia.org/wiki/Crime_in_Washington,_D.C."
    };
    //add feature to map
        pointLayer.addFeatures( [ crimePoint1Feature ] );
    
    //create feature variable for crimePoint2
    crimePoint2Feature = new OpenLayers.Feature.Vector( crimePoint2,null,crimeStyle );
    
    //add attributes to crimePoint2
    crimePoint2Feature.attributes = {
        name: "Burglary",
        description: "Reported 2/25/2011 at 2600 block of Q St SE",
        wikiPage: "http://en.wikipedia.org/wiki/Crime_in_Washington,_D.C."
    };
    //add feature to map
        pointLayer.addFeatures( [ crimePoint2Feature ] );
    
    //create feature variable for crimePoint3
    crimePoint3Feature = new OpenLayers.Feature.Vector( crimePoint3,null,altcrimeStyle );
    
    //add attributes to crimePoint3
    crimePoint3Feature.attributes = {
        name: "Homicide",
        description: "Gun; reported 2/20/2011 at 400 block of 23rd Place NE",
        wikiPage: "http://en.wikipedia.org/wiki/Crime_in_Washington,_D.C."
    };
    //add feature to map
        pointLayer.addFeatures( [ crimePoint3Feature ] );
 
    //create a Control that watches for clicking on a feature, and then add the control to the map
    selectControl = new OpenLayers.Control.SelectFeature( pointLayer );
    map.addControl(selectControl);
    selectControl.activate();
    
    /*the control calls events (featureselected and featureunselected) and we connect those
     events to functions */
    pointLayer.events.on({
        'featureselected': onFeatureSelect,
        'featureunselected': onFeatureUnselect });
    
    function onFeatureSelect(clickInfo) {
        clickedFeature = clickInfo.feature;
        popup = new OpenLayers.Popup.FramedCloud(
                "featurePopup",  // an ID for this popup
                clickedFeature.geometry.getBounds().getCenterLonLat(), // anchor to the icon
                new OpenLayers.Size(120,250),  // set height and width of the window
                "<a target='_blank' href='" + clickedFeature.attributes.wikiPage + "'>" + clickedFeature.attributes.name + "</a><br>" + clickedFeature.attributes.description,  // HTML displayed inside the window
                null,                 // used for other applications
                true,                 // have an [x] to close the Popup
                onPopupClose  // call another function when the Popup is closed
        );
        // let feature and popup 'know' about each other
        clickedFeature.popup = popup;
        popup.feature = clickedFeature;
        // add the popup to the map
        map.addPopup(popup);
    }
 
    function onFeatureUnselect(clickInfo) {
            feature = clickInfo.feature;
            if (feature.popup) {
                    // if an icon with a popup window is un-selected, that popup is removed
                    popup.feature = null;
                    map.removePopup(feature.popup);
                    feature.popup.destroy();
                    feature.popup = null;
            }
    }
 
    function onPopupClose(closeInfo) {
            // closing the Popup un-selects the icon
            selectControl.unselect(this.feature);
    }